Config (Helidon Config 0.10.3 API)

public interface Config

Immutable tree-structured configuration.

Loading Configuration

Load the default configuration using the create() method.


 Config config = Config.create();

Use Config.Builder to construct a new Config instance from one or more specific ConfigSources.

The application can affect the way the system loads configuration by implementing interfaces defined in the SPI, by explicitly constructing the Config.Builder which assembles the Config, and by using other classes provided by the config system that influence loading.

Class.Method	Application-implemented Interface	Purpose
`ConfigSources.from(io.helidon.config.Config)`	`ConfigSource`	Loads configuration from a different type of origin. Each `ConfigSource` implementation handles a type of location. Different instances of a given `ConfigSource` implementation represent separate sources of that location type.
`Config.Builder.addParser(io.helidon.config.spi.ConfigParser)`	`ConfigParser`	Converts one format of config representation into the corresponding `Config` tree.
`Config.Builder.addFilter(io.helidon.config.spi.ConfigFilter)`	`ConfigFilter`	Changes the `String` representation of each config value from one `String` to another as the `Config` tree is built from its sources.
`OverrideSources` methods		Replaces config `String` values during loading based on their keys. Programs provide overrides in Java property file format on the classpath, at a URL, or in a file, or by invoking `OverrideSources.from(java.util.Map<java.lang.String, java.lang.String>)` and passing the name-matching expressions and the corresponding replacement value as a `Map`.
`Config.Builder.addMapper(java.lang.Class<T>, io.helidon.config.ConfigMapper<T>)`	`ConfigMapper`	Implements conversion from a `Config` node (typically with children) to an application-specific Java type.

Navigating in a Configuration Tree

Each loaded configuration is a tree of Config objects. The application can access an arbitrary node in the tree by passing its fully-qualified name to get(java.lang.String):


 Config greeting = config.get("greeting");

Method key() always returns fully-qualified Config.Key of a config node.


 assert greeting.key().toString().equals("greeting")

These are equivalent ways of obtaining the same Config instance, and the two assertions will succeed:


 Config name1 = config.get("app.services.svc1.name");
 Config name2 = config.get("app").get("services.svc1.name");
 Config name3 = config.get("app.services").get("svc1").get("name");
 Config name4 = config.get("app").get("services").get("svc1").get("name");

 assert name4.key().equals(Key.from("app.services.svc1.name"))
 assert name1 == name2 == name3 == name4

The get(java.lang.String) method always returns a Config object, even if no configuration is present using the corresponding key. The application can invoke the type() method to find out the type of the node, represented by one of the Config.Type enum values. The exists() method tells whether or not the Config node represents existing configuration.


 if (!config.get("very.rare.prop42").exists()) {
     // node 'very.rare.prop42' does NOT exist
 }

The traverse() method visits all nodes in a subtree. This example gathers all nodes with keys matching logging.**.level -- that is, all nodes within the "logging" subtree that have a key ending in "level" and also has a single value:


 Map<String,String> loggingLevels = config.get("logging")  // find "logging" subtree
     .traverse()                                           // traverse through logging' nodes
     .filter(node -> node.isLeaf())                        // filter leaf values
     .filter(node -> node.name().equals("level"))          // filter key suffix '.level'
     .collect(Collectors.toMap(Config::key, Config::asString));

To retrieve children of a config node use nodeList(), asNodeList() or asNodeList(List)

on an object node to get all object members,
on a list node to get all list elements.

On a leaf value node get the String value using value(), asString() or asString(String).

Converting Configuration Values to Types

Explicit Conversion by the Application

The interpretation of a configuration node, including what datatype to use, is up to the application. To interpret a node's value as a type other than String the application can invoke one of these convenience methods:

as<typename> such as asBoolean, asDouble, asInt, etc. which return Java primitive data values (boolean, double, int, etc.)
Each method has two variants: one without parameters that throws MissingValueException if the config at the node does not exist, and one that accepts the default value as a single parameter. For example:
```
 long l1 = config.asLong();
 long l2 = config.asLong(42L);
 
```
asOptional<typename> which returns the autoboxed datatype wrapped in an Optional.
For example:
```
 Optional<Long> l3 = config.asOptionalLong();
 
```

as(Class) or as(Class, defaultValue) or asOptional(Class) which return an instance of the requested type.

For example:


 Long l1 = config.as(Long.class);
 Long l2 = config.as(Long.class, 42L);
 Optional<Long> l3 = config.asOptional(Long.class);

Using Built-in and Custom Mappers

Each as* method delegates to a ConfigMapper to convert a config node to a type. The config system provides mappers for primitive datatypes, Lists, and Maps, and automatically registers them with each Config.Builder instance.

To deal with application-specific types, the application can provide its own mapping logic by:

invoking one of the map(java.util.function.Function<java.lang.String, ? extends T>) method variants,
adding custom ConfigMapper implementations using the Config.Builder.addMapper(java.lang.Class<T>, io.helidon.config.ConfigMapper<T>) method,
registering custom mappers using the Java service loader mechanism. (See ConfigMapper for details.)

Returning to the long example:


 long l4 = config.map(ConfigMappers::toLong);
 long l5 = config.map(ConfigMappers::toLong, 42L);
 Optional<Long> l6 = config.mapOptional(ConfigMappers::toLong);

Note that the variants of map accept a Function or a ConfigMapper. The ConfigMappers class implements many useful conversions; check there before writing your own custom mapper.

If there is no explicitly registered ConfigMapper instance in a Config.Builder for converting a given type then the config system uses generic mapping. See ConfigMapperManager for details on how generic mapping works.

Handling Multiple Configuration Sources

A Config instance, including the default Config returned by create(), might be associated with multiple ConfigSources. The config system deals with multiple sources as follows.

The ConfigSources.CompositeBuilder class handles multiple config sources; in fact the config system uses an instance of that builder automatically when your application invokes from(java.util.function.Supplier<io.helidon.config.spi.ConfigSource>...) and withSources(java.util.function.Supplier<io.helidon.config.spi.ConfigSource>...), for example. Each such composite builder has a merging strategy that controls how the config system will search the multiple config sources for a given key. By default each CompositeBuilder uses the FallbackMergingStrategy: configuration sources earlier in the list have a higher priority than the later ones. The system behaves as if, when resolving a value of a key, it checks each source in sequence order. As soon as one source contains a value for the key the system returns that value, ignoring any sources that fall later in the list.

Your application can set a different strategy by constructing its own CompositeBuilder and invoking ConfigSources.CompositeBuilder.mergingStrategy, passing the strategy to be used:

 Config.withSources(ConfigSources.from(source1, source2, source3)
                      .mergingStrategy(new MyMergingStrategy());

Nested Class Summary

Nested Classes
Modifier and Type	Interface	Description
`static interface`	`Config.Builder`	`Config` Builder.
`static interface`	`Config.Context`	Context associated with specific `Config` node that allows to access the last loaded instance of the node or to request reloading of whole configuration.
`static interface`	`Config.Key`	Object represents fully-qualified key of config node.
`static interface`	`Config.Transient`	Annotation used to exclude JavaBean property, method or constructor from JavaBean deserialization support.
`static class`	`Config.Type`	Configuration node types.
`static interface`	`Config.Value`	Annotation used to customize behaviour of JavaBean deserialization support, generic `ConfigMapper` implementation.

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Default Methods Deprecated Methods
Modifier and Type	Method	Description
`default <T> T`	`as(java.lang.Class<? extends T> type)`	Returns typed value as a specified type.
`default <T> T`	`as(java.lang.Class<? extends T> type, T defaultValue)`	Returns typed value as a specified type.
`default boolean`	`asBoolean()`	Returns a `boolean` value of configuration node if the node is `Config.Type.VALUE` and original `value()` can be mapped to.
`default boolean`	`asBoolean(boolean defaultValue)`	Returns a `boolean` value of configuration node if the node is `Config.Type.VALUE` and original `value()` can be mapped to.
`default java.util.function.Supplier<java.lang.Boolean>`	`asBooleanSupplier()`	Returns a supplier of a `Boolean` value of this configuration node.
`default java.util.function.Supplier<java.lang.Boolean>`	`asBooleanSupplier(boolean defaultValue)`	Returns a supplier of a `Boolean` value of this configuration node or a default value.
`default double`	`asDouble()`	Returns a `double` value of configuration node if the node is `Config.Type.VALUE` and original `value()` can be mapped to.
`default double`	`asDouble(double defaultValue)`	Returns a `double` value of configuration node if the node is `Config.Type.VALUE` and original `value()` can be mapped to.
`default java.util.function.Supplier<java.lang.Double>`	`asDoubleSupplier()`	Returns a supplier of a `Double` value of this configuration node.
`default java.util.function.Supplier<java.lang.Double>`	`asDoubleSupplier(double defaultValue)`	Returns a supplier of a `Double` value of this configuration node or a default value.
`default int`	`asInt()`	Returns a `int` value of configuration node if the node is `Config.Type.VALUE` and original `value()` can be mapped to.
`default int`	`asInt(int defaultValue)`	Returns a `int` value of configuration node if the node is `Config.Type.VALUE` and original `value()` can be mapped to.
`default java.util.function.Supplier<java.lang.Integer>`	`asIntSupplier()`	Returns a supplier of a `Integer` value of this configuration node.
`default java.util.function.Supplier<java.lang.Integer>`	`asIntSupplier(int defaultValue)`	Returns a supplier of a `Integer` value of this configuration node or a default value.
`default <T> java.util.List<T>`	`asList(java.lang.Class<? extends T> type)`	Returns list of specified type.
`default <T> java.util.List<T>`	`asList(java.lang.Class<? extends T> type, java.util.List<T> defaultValue)`	Returns list of specified type.
`default <T> java.util.function.Supplier<java.util.List<T>>`	`asListSupplier(java.lang.Class<? extends T> type)`	Returns a supplier of a list of specified type.
`default <T> java.util.function.Supplier<java.util.List<T>>`	`asListSupplier(java.lang.Class<? extends T> type, java.util.List<T> defaultValue)`	Returns a supplier of a list of a specified type or a default value.
`default long`	`asLong()`	Returns a `long` value of configuration node if the node is `Config.Type.VALUE` and original `value()` can be mapped to.
`default long`	`asLong(long defaultValue)`	Returns a `long` value of configuration node if the node is `Config.Type.VALUE` and original `value()` can be mapped to.
`default java.util.function.Supplier<java.lang.Long>`	`asLongSupplier()`	Returns a supplier of a `Long` value of this configuration node.
`default java.util.function.Supplier<java.lang.Long>`	`asLongSupplier(long defaultValue)`	Returns a supplier of a `Long` value of this configuration node or a default value.
`default java.util.Map<java.lang.String,java.lang.String>`	`asMap()`	Transform all leaf nodes (values) into Map instance.
`default java.util.Map<java.lang.String,java.lang.String>`	`asMap(java.util.Map<java.lang.String,java.lang.String> defaultValue)`	Transform all leaf nodes (values) into Map instance.
`default java.util.function.Supplier<java.util.Map<java.lang.String,java.lang.String>>`	`asMapSupplier()`	Returns a supplier of a map with transformed leaf nodes.
`default java.util.function.Supplier<java.util.Map<java.lang.String,java.lang.String>>`	`asMapSupplier(java.util.Map<java.lang.String,java.lang.String> defaultValue)`	Returns a supplier of a map with transformed leaf nodes or a default value if this node is `Config.Type.MISSING`.
`default java.util.List<Config>`	`asNodeList()`	Returns a list of child `Config` nodes if the node is `Config.Type.OBJECT`.
`default java.util.List<Config>`	`asNodeList(java.util.List<Config> defaultValue)`	Returns a list of child `Config` nodes if the node is `Config.Type.OBJECT`.
`default java.util.function.Supplier<java.util.List<Config>>`	`asNodeListSupplier()`	Returns a supplier of a list of child nodes when this node is `Config.Type.OBJECT` or a list of element nodes for `Config.Type.LIST`.
`default java.util.function.Supplier<java.util.List<Config>>`	`asNodeListSupplier(java.util.List<Config> defaultValue)`	Returns a supplier of a list of child nodes when this node is `Config.Type.OBJECT`, a list of element nodes for `Config.Type.LIST` or `defaultValue` if this node is `Config.Type.MISSING`.
`<T> java.util.Optional<T>`	`asOptional(java.lang.Class<? extends T> type)`	Returns typed value as a specified type.
`default java.util.Optional<java.lang.Boolean>`	`asOptionalBoolean()`	Maps the node `value()` to `Optional`.
`default java.util.function.Supplier<java.util.Optional<java.lang.Boolean>>`	`asOptionalBooleanSupplier()`	Returns a supplier to a value typed as an `Optional`.
`default java.util.OptionalDouble`	`asOptionalDouble()`	Maps the node `value()` to `OptionalDouble`.
`default java.util.function.Supplier<java.util.OptionalDouble>`	`asOptionalDoubleSupplier()`	Returns a supplier to a value typed as an `OptionalDouble`.
`default java.util.OptionalInt`	`asOptionalInt()`	Maps the node `value()` to `OptionalInt`.
`default java.util.function.Supplier<java.util.OptionalInt>`	`asOptionalIntSupplier()`	Returns a supplier to a value typed as an `OptionalInt`.
`<T> java.util.Optional<java.util.List<T>>`	`asOptionalList(java.lang.Class<? extends T> type)`	Returns list of specified type (single values as well as objects).
`default <T> java.util.function.Supplier<java.util.Optional<java.util.List<T>>>`	`asOptionalListSupplier(java.lang.Class<? extends T> type)`	Returns a supplier of as optional list of typed values.
`default java.util.OptionalLong`	`asOptionalLong()`	Maps the node `value()` to `OptionalLong`.
`default java.util.function.Supplier<java.util.OptionalLong>`	`asOptionalLongSupplier()`	Returns a supplier to a value typed as an `OptionalLong`.
`java.util.Optional<java.util.Map<java.lang.String,java.lang.String>>`	`asOptionalMap()`	Transform all leaf nodes (values) into Map instance.
`default java.util.function.Supplier<java.util.Optional<java.util.Map<java.lang.String,java.lang.String>>>`	`asOptionalMapSupplier()`	Returns a `Supplier` of a transformed leaf nodes (values) into a Map instance.
`default java.util.Optional<java.util.List<Config>>`	`asOptionalNodeList()`	Returns a list of child `Config` nodes if the node is `Config.Type.OBJECT`.
`default java.util.function.Supplier<java.util.Optional<java.util.List<Config>>>`	`asOptionalNodeListSupplier()`	Returns a `Supplier` of a list of child `Config` nodes if the node is `Config.Type.OBJECT`.
`default java.util.Optional<java.lang.String>`	`asOptionalString()`	Returns a `String` value as `Optional` of configuration node if the node is `Config.Type.VALUE`.
`default java.util.Optional<java.util.List<java.lang.String>>`	`asOptionalStringList()`	Returns list of `String`.
`default java.util.function.Supplier<java.util.Optional<java.util.List<java.lang.String>>>`	`asOptionalStringListSupplier()`	Returns a supplier of as optional list of `String`.
`default java.util.function.Supplier<java.util.Optional<java.lang.String>>`	`asOptionalStringSupplier()`	Returns a `Supplier` of an `Optional<String>` of the configuration node if the node is `Config.Type.VALUE`.
`default <T> java.util.function.Supplier<java.util.Optional<T>>`	`asOptionalSupplier(java.lang.Class<? extends T> type)`	Returns a supplier of an optional typed value.
`default java.lang.String`	`asString()`	Returns a `String` value of configuration node if the node is `Config.Type.VALUE`.
`default java.lang.String`	`asString(java.lang.String defaultValue)`	Returns a `String` value of configuration node if the node is `Config.Type.VALUE`.
`default java.util.List<java.lang.String>`	`asStringList()`	Returns a list of `String`s mapped from `Config.Type.LIST` or `Config.Type.OBJECT` `nodes`.
`default java.util.List<java.lang.String>`	`asStringList(java.util.List<java.lang.String> defaultValue)`	Returns a list of `String`s mapped from `Config.Type.LIST` or `Config.Type.OBJECT` `nodes`.
`default java.util.function.Supplier<java.util.List<java.lang.String>>`	`asStringListSupplier()`	Returns a supplier to a list of `String`s mapped from `Config.Type.LIST` or `Config.Type.OBJECT` `nodes`.
`default java.util.function.Supplier<java.util.List<java.lang.String>>`	`asStringListSupplier(java.util.List<java.lang.String> defaultValue)`	Returns a supplier to a list of `String`s mapped from `Config.Type.LIST` or `Config.Type.OBJECT` `nodes` or a default value.
`default java.util.function.Supplier<java.lang.String>`	`asStringSupplier()`	Returns a supplier of a `String` value of this configuration node.
`default java.util.function.Supplier<java.lang.String>`	`asStringSupplier(java.lang.String defaultValue)`	Returns a supplier of a `String` value of this configuration node or a default value.
`default <T> java.util.function.Supplier<T>`	`asSupplier(java.lang.Class<? extends T> type)`	Returns a supplier of a typed value.
`default <T> java.util.function.Supplier<T>`	`asSupplier(java.lang.Class<? extends T> type, T defaultValue)`	Returns a supplier of a typed value.
`static Config.Builder`	`builder()`	Provides a `Config.Builder` for creating a `Config` instance.
`default io.helidon.common.reactive.Flow.Publisher<Config>`	`changes()`	Deprecated.
`default Config.Context`	`context()`	Returns the `Context` instance associated with the current `Config` node that allows the application to access the last loaded instance of the node or to request that the entire configuration be reloaded.
`static Config`	`create()`	Returns a new default `Config` loaded using one of the configuration files available on the classpath and/or using the runtime environment.
`Config`	`detach()`	Returns a copy of the `Config` node with no parent.
`static Config`	`empty()`	Returns empty instance of `Config`.
`default boolean`	`exists()`	Returns `true` if the node exists, whether an object, a list, or a value node.
`static Config`	`from(java.util.function.Supplier<ConfigSource>... configSources)`	Creates a new `Config` loaded from environment variables, system properties, and the specified `ConfigSource`s.
`Config`	`get(Config.Key key)`	Returns the single sub-node for the specified sub-key.
`default Config`	`get(java.lang.String key)`	Returns the single sub-node for the specified sub-key.
`boolean`	`hasValue()`	Returns `true` if this configuration node has a direct value.
`default void`	`ifExists(java.util.function.Consumer<Config> action)`	Performs the given action with the config node if node `exists`, otherwise does nothing.
`default void`	`ifExistsOrElse(java.util.function.Consumer<Config> action, java.lang.Runnable missingAction)`	Performs the given action with the config node if the node `exists`, otherwise performs the specified "missing" action.
`default boolean`	`isLeaf()`	Returns `true` if this node exists and is a leaf node (has no children).
`Config.Key`	`key()`	Returns the fully-qualified key of the `Config` node.
`static Config.Builder`	`loadSources(java.util.function.Supplier<ConfigSource>... metaSources)`	Provides a `Config.Builder` for creating a `Config` based on the specified `ConfigSource`s representing meta-configurations.
`static Config`	`loadSourcesFrom(java.util.function.Supplier<ConfigSource>... metaSources)`	Creates a new `Config` loaded from the specified `ConfigSource`s representing meta-configurations.
`default <T> T`	`map(ConfigMapper<? extends T> mapper)`	Returns typed value as a using specified config hierarchy mapper.
`default <T> T`	`map(ConfigMapper<? extends T> mapper, T defaultValue)`	Returns typed value as a using specified config hierarchy mapper.
`default <T> T`	`map(java.util.function.Function<java.lang.String,? extends T> mapper)`	Returns typed value as a using specified type mapper.
`default <T> T`	`map(java.util.function.Function<java.lang.String,? extends T> mapper, T defaultValue)`	Returns typed value as a using specified type mapper.
`default <T> java.util.List<T>`	`mapList(ConfigMapper<? extends T> mapper)`	Returns typed list of type provided by specified type mapper.
`default <T> java.util.List<T>`	`mapList(ConfigMapper<? extends T> mapper, java.util.List<T> defaultValue)`	Returns typed list of type provided by specified type mapper.
`default <T> java.util.List<T>`	`mapList(java.util.function.Function<java.lang.String,? extends T> mapper)`	Returns typed list of type provided by specified config hierarchy mapper.
`default <T> java.util.List<T>`	`mapList(java.util.function.Function<java.lang.String,? extends T> mapper, java.util.List<T> defaultValue)`	Returns typed list of type provided by specified config hierarchy mapper.
`default <T> java.util.function.Supplier<java.util.List<T>>`	`mapListSupplier(ConfigMapper<? extends T> mapper)`	Returns a supplier of a list of a type provided by a specified type mapper.
`default <T> java.util.function.Supplier<java.util.List<T>>`	`mapListSupplier(ConfigMapper<? extends T> mapper, java.util.List<T> defaultValue)`	Returns a supplier of a list of a type provided by a specified type mapper or a default value.
`default <T> java.util.function.Supplier<java.util.List<T>>`	`mapListSupplier(java.util.function.Function<java.lang.String,? extends T> mapper)`	Returns a supplier of a list of a type provided by a specified type mapper.
`default <T> java.util.function.Supplier<java.util.List<T>>`	`mapListSupplier(java.util.function.Function<java.lang.String,? extends T> mapper, java.util.List<T> defaultValue)`	Returns a supplier of a list of a type provided by a specified type mapper or a default value.
`default <T> java.util.Optional<T>`	`mapOptional(ConfigMapper<? extends T> mapper)`	Returns typed value as a using specified type mapper.
`default <T> java.util.Optional<T>`	`mapOptional(java.util.function.Function<java.lang.String,? extends T> mapper)`	Returns typed value as a using specified type mapper.
`default <T> java.util.Optional<java.util.List<T>>`	`mapOptionalList(ConfigMapper<? extends T> mapper)`	Returns typed list of type (single values as well as objects) provided by specified type mapper.
`default <T> java.util.Optional<java.util.List<T>>`	`mapOptionalList(java.util.function.Function<java.lang.String,? extends T> mapper)`	Returns typed list of type (single values as well as objects) provided by specified type mapper.
`default <T> java.util.function.Supplier<java.util.Optional<java.util.List<T>>>`	`mapOptionalListSupplier(ConfigMapper<? extends T> mapper)`	Returns a supplier of an optional typed list of a type (single values as well as objects) provided by a specified type mapper.
`default <T> java.util.function.Supplier<java.util.Optional<java.util.List<T>>>`	`mapOptionalListSupplier(java.util.function.Function<java.lang.String,? extends T> mapper)`	Returns a supplier of an optional typed list of a type (single values as well as objects) provided by a specified type mapper.
`default <T> java.util.function.Supplier<java.util.Optional<T>>`	`mapOptionalSupplier(ConfigMapper<? extends T> mapper)`	Returns a supplier of an optional value, typed using a specified type mapper.
`default <T> java.util.function.Supplier<java.util.Optional<T>>`	`mapOptionalSupplier(java.util.function.Function<java.lang.String,? extends T> mapper)`	Returns a supplier of an optional value, typed using a specified type mapper.
`default <T> java.util.function.Supplier<T>`	`mapSupplier(ConfigMapper<? extends T> mapper)`	Returns a supplier of a typed value, using a specified type mapper.
`default <T> java.util.function.Supplier<T>`	`mapSupplier(ConfigMapper<? extends T> mapper, T defaultValue)`	Returns a supplier of a typed value, using a specified type mapper or a default value.
`default <T> java.util.function.Supplier<T>`	`mapSupplier(java.util.function.Function<java.lang.String,? extends T> mapper)`	Returns a supplier of a typed value, using a specified type mapper.
`default <T> java.util.function.Supplier<T>`	`mapSupplier(java.util.function.Function<java.lang.String,? extends T> mapper, T defaultValue)`	Returns a supplier of a typed value, using a specified type mapper or a default value.
`default java.lang.String`	`name()`	Returns the last token of the fully-qualified key for the `Config` node.
`default java.util.Optional<Config>`	`node()`	Returns existing current config node as a `Optional` instance or `Optional.empty()` in case of `Config.Type.MISSING` node.
`java.util.Optional<java.util.List<Config>>`	`nodeList()`	Returns a list of child `Config` nodes if the node is `Config.Type.OBJECT`.
`default java.util.function.Supplier<java.util.Optional<Config>>`	`nodeSupplier()`	Returns a `Supplier` of the configuration node as an `Optional<Config>` or `Optional.empty()` if the node is `Config.Type.MISSING`.
`default void`	`onChange(java.util.function.Function<Config,java.lang.Boolean> onNextFunction)`	Directly subscribes `onNextFunction` function on change on whole Config or on particular Config node.
`java.time.Instant`	`timestamp()`	Returns when the configuration tree was created.
`default java.util.stream.Stream<Config>`	`traverse()`	Iterative deepening depth-first traversal of the node and its subtree as a `Stream<Config>`.
`java.util.stream.Stream<Config>`	`traverse(java.util.function.Predicate<Config> predicate)`	Iterative deepening depth-first traversal of the node and its subtree as a `Stream<Config>`, qualified by the specified predicate.
`Config.Type`	`type()`	Provides the `Config.Type` of the `Config` node.
`java.util.Optional<java.lang.String>`	`value()`	Returns a `String` value as `Optional` of configuration node if the node is `Config.Type.VALUE`.
`static Config.Builder`	`withSources(java.util.function.Supplier<ConfigSource>... configSources)`	Provides a `Config.Builder` for creating a `Config` based on the specified `ConfigSource` instances.

- Method Detail
  - empty
```
static Config empty()
```
    Returns empty instance of Config.
    
    Returns:
    
    empty instance of Config.
  - create
```
static Config create()
```
    Returns a new default Config loaded using one of the configuration files available on the classpath and/or using the runtime environment.
    The config system loads the default configuration using a default Config.Builder which loads configuration data as described below. In contrast, the application can control how and from where configuration is loaded by explicitly creating and fine-tuning one or more Builder instances itself.
    1. Meta-configuration
      Meta-configuration specifies at least one ConfigSource or Config.Builder from which the system can load configuration. The config system searches for at most one of the following meta-configuration locations on the classpath, in this order:
      
      meta-config.yaml - meta configuration file in YAML format
      
      meta-config.conf - meta configuration file in HOCON format
      
      meta-config.json - meta configuration file in JSON format
      
      meta-config.properties - meta configuration file in Java Properties format
    2. Configuration
      In the absence of meta-configuration the config system loads the default configuration from all of the following sources:
      
      environment variables;
      
      system properties
      
      at most one of following locations on the classpath, in this order:
      
      application.yaml - configuration file in YAML format
      
      application.conf - configuration file in HOCON format
      
      application.json - configuration file in JSON format
      
      application.properties - configuration file in Java Properties format
      
      The config system uses only the first application.* location it finds for which it can locate a ConfigParser that supports the corresponding media type.
      When creating the default configuration the config system detects parsers that were loaded using the ServiceLoader mechanism or, if it finds none loaded, a built-in parser provided by the config system.
    Every invocation of this method creates a new Config instance which has neither a polling strategy nor a retry policy. To set up these and other behaviors the application should create explicitly a Config.Builder, tailor it accordingly, and then use its build method to create the Config instance as desired.
    Returns:
    
    new instance of Config
    
    See Also:
    
    loadSourcesFrom(Supplier[])
  - from
```
@SafeVarargs
static Config from(java.util.function.Supplier<ConfigSource>... configSources)
```
    Creates a new Config loaded from environment variables, system properties, and the specified ConfigSources.
    The resulting configuration uses the following sources, in order:
    1. environment variables config source
      Can disabled by Config.Builder.disableEnvironmentVariablesSource()
    2. system properties config source Can disabled by Config.Builder.disableSystemPropertiesSource()
    3. Source(s) specified by user in the method.
    See multiple sources for more information.
    Parameters:
    
    configSources - ordered list of configuration sources
    
    Returns:
    
    new instance of Config
    
    See Also:
    
    loadSourcesFrom(Supplier[]), withSources(Supplier[]), loadSources(Supplier[]), Config.Builder.sources(List), Config.Builder.disableEnvironmentVariablesSource(), Config.Builder.disableSystemPropertiesSource(), ConfigSources.from(Supplier[]), ConfigSources.CompositeBuilder, ConfigSources.MergingStrategy
  - loadSourcesFrom
```
@SafeVarargs
static Config loadSourcesFrom(java.util.function.Supplier<ConfigSource>... metaSources)
```
    Creates a new Config loaded from the specified ConfigSources representing meta-configurations.
    See ConfigSource.from(Config) for more information about the format of meta-configuration.
    
    Parameters:
    
    metaSources - ordered list of meta sources
    
    Returns:
    
    new instance of Config
    
    See Also:
    
    from(Supplier[]), withSources(Supplier[]), loadSources(Supplier[]), ConfigSources.load(Supplier[])
  - withSources
```
@SafeVarargs
static Config.Builder withSources(java.util.function.Supplier<ConfigSource>... configSources)
```
    Provides a Config.Builder for creating a Config based on the specified ConfigSource instances.
    The resulting configuration uses the following sources, in order:
    1. environment variables
      Can be disabled by invoking Config.Builder.disableEnvironmentVariablesSource()
    2. system properties config source
      Can be disabled by invoking Config.Builder.disableSystemPropertiesSource()
    3. source(s) passed in the method invocation
    See multiple sources for more information.
    Parameters:
    
    configSources - ordered list of configuration sources
    
    Returns:
    
    new initialized Builder instance
    
    See Also:
    
    builder(), from(Supplier[]), loadSourcesFrom(Supplier[]), loadSources(Supplier[]), Config.Builder.sources(List), Config.Builder.disableEnvironmentVariablesSource(), Config.Builder.disableSystemPropertiesSource(), ConfigSources.from(Supplier[]), ConfigSources.CompositeBuilder, ConfigSources.MergingStrategy
  - loadSources
```
@SafeVarargs
static Config.Builder loadSources(java.util.function.Supplier<ConfigSource>... metaSources)
```
    Provides a Config.Builder for creating a Config based on the specified ConfigSources representing meta-configurations.
    Each meta-configuration source should set the sources property to be an array of config sources. See ConfigSource.from(Config) for more information about the format of meta-configuration.
    
    Parameters:
    
    metaSources - ordered list of meta sources
    
    Returns:
    
    new initialized Builder instance
    
    See Also:
    
    builder(), withSources(Supplier[]), ConfigSources.load(Supplier[]), loadSourcesFrom(Supplier[])
  - builder
```
static Config.Builder builder()
```
    Provides a Config.Builder for creating a Config instance.
    
    Returns:
    
    new Builder instance
  - context
```
default Config.Context context()
```
    Returns the Context instance associated with the current Config node that allows the application to access the last loaded instance of the node or to request that the entire configuration be reloaded.
    
    Returns:
    
    Context instance associated with specific Config node
  - timestamp
```
java.time.Instant timestamp()
```
    Returns when the configuration tree was created.
    Each config node of single Config tree returns same timestamp.
    
    Returns:
    
    timestamp of created instance of whole configuration tree.
    
    See Also:
    
    context(), Config.Context.timestamp()
  - key
```
Config.Key key()
```
    Returns the fully-qualified key of the Config node.
    The fully-qualified key is a sequence of tokens derived from the name of each node along the path from the config root to the current node. Tokens are separated by . (the dot character). See name() for more information on the format of each token.
    
    Returns:
    
    current config node key
    
    See Also:
    
    name()
  - name
```
default java.lang.String name()
```
    Returns the last token of the fully-qualified key for the Config node.
    The name of a node is the last token in its fully-qualified key.
    The exact format of the name depends on the Type of the containing node:
    - from a Config.Type.OBJECT node the token for a child is the name of the object member;
    - from a Config.Type.LIST node the token for a child is a zero-based index of the element, an unsigned base-10 integer value with no leading zeros.
    The ABNF syntax of config key is:
```
 config-key = *1( key-token *( "." key-token ) )
  key-token = *( unescaped / escaped )
  unescaped = %x00-2D / %x2F-7D / %x7F-10FFFF
            ; %x2E ('.') and %x7E ('~') are excluded from 'unescaped'
    escaped = "~" ( "0" / "1" )
            ; representing '~' and '.', respectively
 
```
    Returns:
    
    current config node key
    
    See Also:
    
    key(), Config.Key.name()
  - get
```
default Config get(java.lang.String key)
```
    Returns the single sub-node for the specified sub-key.
    The format of the key is described on key() method.
    
    Parameters:
    
    key - sub-key of requested sub-node
    
    Returns:
    
    config node for specified sub-key, never returns null.
    
    See Also:
    
    get(Key)
  - get
```
Config get(Config.Key key)
```
    Returns the single sub-node for the specified sub-key.
    
    Parameters:
    
    key - sub-key of requested sub-node
    
    Returns:
    
    config node for specified sub-key, never returns null.
    
    See Also:
    
    get(String)
  - detach
```
Config detach()
```
    Returns a copy of the Config node with no parent.
    The returned node acts as a root node for the subtree below it. Its key is the empty string; "". The original config node is unchanged, and the original and the copy point to the same children.
    Consider the following configuration:
```
 app:
      name: Example 1
      page-size: 20
 logging:
      app.level = INFO
      level = WARNING
 
```
    The Config instances name1 and name2 represents same data and in fact refer to the same object:
```
 Config name1 = config
                  .get("app")
                  .get("name");
 Config name2 = config
                  .get("app")
                  .detach()               //DETACHED node
                  .get("name");

 assert name1.asString() == "Example 1";
 assert name2.asString() == "Example 1";  //DETACHED node
 
```
    The only difference is the key each node returns:
```
 assert name1.key() == "app.name";
 assert name2.key() == "name";            //DETACHED node
 
```
    See asOptionalMap() for example of config detaching.
    Returns:
    
    returns detached Config instance of same config node
  - type
```
Config.Type type()
```
    Provides the Config.Type of the Config node.
    
    Returns:
    
    the Type of the configuration node
  - exists
```
default boolean exists()
```
    Returns true if the node exists, whether an object, a list, or a value node.
    
    Returns:
    
    true if the node exists
  - isLeaf
```
default boolean isLeaf()
```
    Returns true if this node exists and is a leaf node (has no children).
    A leaf node has no nested configuration subtree and has a single value.
    
    Returns:
    
    true if the node is existing leaf node, false otherwise.
  - hasValue
```
boolean hasValue()
```
    Returns true if this configuration node has a direct value.
    This may be a value node (e.g. a leaf) or object node or a list node (e.g. a branch with value). The application can invoke methods such as as(Class) on nodes that have value.
    
    Returns:
    
    true if the node has direct value, false otherwise.
  - ifExists
```
default void ifExists(java.util.function.Consumer<Config> action)
```
    Performs the given action with the config node if node exists, otherwise does nothing.
    
    Parameters:
    
    action - the action to be performed if the node exists
    
    See Also:
    
    exists(), type()
  - ifExistsOrElse
```
default void ifExistsOrElse(java.util.function.Consumer<Config> action,
                            java.lang.Runnable missingAction)
```
    Performs the given action with the config node if the node exists, otherwise performs the specified "missing" action.
    
    Parameters:
    
    action - the action to be performed, if a config node exists
    
    missingAction - the missing-based action to be performed, if a config node is missing.
    
    See Also:
    
    exists(), type()
  - traverse
```
default java.util.stream.Stream<Config> traverse()
```
    Iterative deepening depth-first traversal of the node and its subtree as a Stream<Config>.
    If the config node does not exist or is a leaf the returned stream is empty.
    Depending on the structure of the configuration the returned stream can deliver a mix of object, list, and leaf value nodes. The stream will include and traverse through object members and list elements.
    
    Returns:
    
    stream of deepening depth-first sub-nodes
  - traverse
```
java.util.stream.Stream<Config> traverse(java.util.function.Predicate<Config> predicate)
```
    Iterative deepening depth-first traversal of the node and its subtree as a Stream<Config>, qualified by the specified predicate.
    If the config node does not exist or is a leaf the returned stream is empty.
    Depending on the structure of the configuration the returned stream can deliver a mix of object, list, and leaf value nodes. The stream will include and traverse through object members and list elements.
    The traversal continues as long as the specified predicate evaluates to true. When the predicate evaluates to false the node being traversed and its subtree will be excluded from the returned Stream<Config>.
    
    Parameters:
    
    predicate - predicate evaluated on each visited Config node to continue or stop visiting the node
    
    Returns:
    
    stream of deepening depth-first subnodes
  - value
```
java.util.Optional<java.lang.String> value()
                                    throws ConfigMappingException
```
    Returns a String value as Optional of configuration node if the node is Config.Type.VALUE. Returns a empty if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Returns:
    
    value as type instance as Optional, empty in case the node is Config.Type.MISSING
    
    Throws:
    
    ConfigMappingException - in case the node is Config.Type.OBJECT or Config.Type.LIST
    
    See Also:
    
    asOptionalString()
  - asOptionalString
```
default java.util.Optional<java.lang.String> asOptionalString()
                                                       throws ConfigMappingException
```
    Returns a String value as Optional of configuration node if the node is Config.Type.VALUE. Returns a empty if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Returns:
    
    value as type instance as Optional, empty in case the node is Config.Type.MISSING
    
    Throws:
    
    ConfigMappingException - in case the node is Config.Type.OBJECT or Config.Type.LIST
    
    See Also:
    
    value(), asOptionalStringSupplier()
  - asOptionalStringSupplier
```
default java.util.function.Supplier<java.util.Optional<java.lang.String>> asOptionalStringSupplier()
```
    Returns a Supplier of an Optional<String> of the configuration node if the node is Config.Type.VALUE. Supplier returns a empty if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Returns:
    
    a supplier of the value as an Optional typed instance, empty in case the node is Config.Type.MISSING
    
    See Also:
    
    asOptionalString()
  - node
```
default java.util.Optional<Config> node()
```
    Returns existing current config node as a Optional instance or Optional.empty() in case of Config.Type.MISSING node.
    
    Returns:
    
    current config node as a Optional instance or Optional.empty() in case of Config.Type.MISSING node.
    
    See Also:
    
    nodeSupplier()
  - nodeSupplier
```
default java.util.function.Supplier<java.util.Optional<Config>> nodeSupplier()
```
    Returns a Supplier of the configuration node as an Optional<Config> or Optional.empty() if the node is Config.Type.MISSING.
    
    Returns:
    
    a Supplier of the configuration node as an Optional<Config> or Optional.empty() if the node is Config.Type.MISSING
    
    See Also:
    
    asOptionalStringSupplier(), node()
  - nodeList
```
java.util.Optional<java.util.List<Config>> nodeList()
                                             throws ConfigMappingException
```
    Returns a list of child Config nodes if the node is Config.Type.OBJECT. Returns a list of element nodes if the node is Config.Type.LIST. Returns an Optional.empty() if the node is Config.Type.MISSING. Otherwise, if node is Config.Type.VALUE, it throws ConfigMappingException.
    
    Returns:
    
    list of Config.Type.OBJECT members, list of Config.Type.LIST members or empty list in case of Config.Type.MISSING
    
    Throws:
    
    ConfigMappingException - in case the node is Config.Type.VALUE
    
    See Also:
    
    asOptionalNodeList()
  - asOptionalNodeList
```
default java.util.Optional<java.util.List<Config>> asOptionalNodeList()
                                                               throws ConfigMappingException
```
    Returns a list of child Config nodes if the node is Config.Type.OBJECT. Returns a list of element nodes if the node is Config.Type.LIST. Returns an empty list if the node is Config.Type.MISSING. Otherwise, if node is Config.Type.VALUE, it throws ConfigMappingException.
    
    Returns:
    
    list of Config.Type.OBJECT members, list of Config.Type.LIST members or empty list in case of Config.Type.MISSING
    
    Throws:
    
    ConfigMappingException - in case the node is Config.Type.VALUE
    
    See Also:
    
    nodeList(), asOptionalNodeListSupplier()
  - asOptionalNodeListSupplier
```
default java.util.function.Supplier<java.util.Optional<java.util.List<Config>>> asOptionalNodeListSupplier()
```
    Returns a Supplier of a list of child Config nodes if the node is Config.Type.OBJECT. Returns a Supplier of a list of element nodes if the node is Config.Type.LIST. Returns a Supplier of an empty list if the node is Config.Type.MISSING. Otherwise, if node is Config.Type.VALUE, a calling of Supplier.get() causes ConfigMappingException.
    
    Returns:
    
    a supplier of a list of Config.Type.OBJECT members, a list of Config.Type.LIST members or an empty list in case of Config.Type.MISSING
    
    See Also:
    
    nodeList(), asOptionalNodeList()
  - asOptionalMap
```
java.util.Optional<java.util.Map<java.lang.String,java.lang.String>> asOptionalMap()
```
    Transform all leaf nodes (values) into Map instance.
    Fully qualified key of config node is used as a key in returned Map. Detach config node before transforming to Map in case you want to cut current Config node key prefix.
    Let's say we work with following configuration:
```
 app:
      name: Example 1
      page-size: 20
 logging:
      app.level = INFO
      level = WARNING
 
```
    Map app1 contains two keys: app.name, app.page-size.
```
 Map<String, String> app1 = config.get("app").asOptionalMap().get();
 
```
    Detaching app config node returns new Config instance with "reset" local root.
```
 Map<String, String> app2 = config.get("app").detach().asOptionalMap().get();
 
```
    Map app2 contains two keys without app prefix: name, page-size.
    Returns:
    
    map as Optional, empty in case of Config.Type.MISSING node
    
    See Also:
    
    asMap(), asMap(Map), traverse(), detach()
  - asOptionalMapSupplier
```
default java.util.function.Supplier<java.util.Optional<java.util.Map<java.lang.String,java.lang.String>>> asOptionalMapSupplier()
```
    Returns a Supplier of a transformed leaf nodes (values) into a Map instance.
    See asOptionalMap() to more detailed about the result.
    
    Returns:
    
    a supplier of optional transformed leaf nodes to map
    
    See Also:
    
    asOptionalMap()
  - asOptional
```
<T> java.util.Optional<T> asOptional(java.lang.Class<? extends T> type)
                              throws ConfigMappingException
```
    Returns typed value as a specified type.
    
    Type Parameters:
    
    T - type
    
    Parameters:
    
    type - type class
    
    Returns:
    
    value as type instance as Optional, empty if entry does not have set value
    
    Throws:
    
    ConfigMappingException - in case of problem to map property value.
  - asOptionalSupplier
```
default <T> java.util.function.Supplier<java.util.Optional<T>> asOptionalSupplier(java.lang.Class<? extends T> type)
```
    Returns a supplier of an optional typed value.
    
    Type Parameters:
    
    T - a type
    
    Parameters:
    
    type - a type class
    
    Returns:
    
    a supplier of a value as type instance as Optional, empty if entry does not have set value
    
    See Also:
    
    asOptional(Class)
  - asOptionalList
```
<T> java.util.Optional<java.util.List<T>> asOptionalList(java.lang.Class<? extends T> type)
                                                  throws ConfigMappingException
```
    Returns list of specified type (single values as well as objects).
    
    Type Parameters:
    
    T - type
    
    Parameters:
    
    type - type class
    
    Returns:
    
    typed list as Optional, empty if entry does not have set value
    
    Throws:
    
    ConfigMappingException - in case of problem to map property value.
  - asOptionalListSupplier
```
default <T> java.util.function.Supplier<java.util.Optional<java.util.List<T>>> asOptionalListSupplier(java.lang.Class<? extends T> type)
```
    Returns a supplier of as optional list of typed values.
    
    Type Parameters:
    
    T - a type
    
    Parameters:
    
    type - a type class
    
    Returns:
    
    a supplier of as optional list of typed values
    
    See Also:
    
    asOptionalList(Class)
  - asOptionalStringList
```
default java.util.Optional<java.util.List<java.lang.String>> asOptionalStringList()
                                                                           throws ConfigMappingException
```
    Returns list of String.
    
    Returns:
    
    typed list as Optional, empty if entry does not have set value
    
    Throws:
    
    ConfigMappingException - in case of problem to map property value.
  - asOptionalStringListSupplier
```
default java.util.function.Supplier<java.util.Optional<java.util.List<java.lang.String>>> asOptionalStringListSupplier()
```
    Returns a supplier of as optional list of String.
    
    Returns:
    
    a supplier of as optional list of String
    
    See Also:
    
    asOptionalStringList()
  - mapOptional
```
default <T> java.util.Optional<T> mapOptional(java.util.function.Function<java.lang.String,? extends T> mapper)
                                       throws ConfigMappingException
```
    Returns typed value as a using specified type mapper.
    
    Type Parameters:
    
    T - type
    
    Parameters:
    
    mapper - type mapper
    
    Returns:
    
    value as type instance as Optional, empty if entry does not have set value
    
    Throws:
    
    ConfigMappingException - in case of problem to map property value.
  - mapOptionalSupplier
```
default <T> java.util.function.Supplier<java.util.Optional<T>> mapOptionalSupplier(java.util.function.Function<java.lang.String,? extends T> mapper)
```
    Returns a supplier of an optional value, typed using a specified type mapper.
    
    Type Parameters:
    
    T - a type
    
    Parameters:
    
    mapper - a type mapper
    
    Returns:
    
    a supplier of an optional value, typed using a specified type mapper
    
    See Also:
    
    mapOptional(Function)
  - mapOptional
```
default <T> java.util.Optional<T> mapOptional(ConfigMapper<? extends T> mapper)
                                       throws ConfigMappingException
```
    Returns typed value as a using specified type mapper.
    
    Type Parameters:
    
    T - expected Java type
    
    Parameters:
    
    mapper - configuration hierarchy mapper.
    
    Returns:
    
    value as type instance as Optional, empty if entry does not represent an existing configuration node.
    
    Throws:
    
    ConfigMappingException - in case of problem to map property value.
  - mapOptionalSupplier
```
default <T> java.util.function.Supplier<java.util.Optional<T>> mapOptionalSupplier(ConfigMapper<? extends T> mapper)
```
    Returns a supplier of an optional value, typed using a specified type mapper.
    
    Type Parameters:
    
    T - an expected Java type
    
    Parameters:
    
    mapper - a configuration mapper
    
    Returns:
    
    a supplier of an optional value, typed using a specified type mapper
    
    See Also:
    
    mapOptional(ConfigMapper)
  - asOptionalBoolean
```
default java.util.Optional<java.lang.Boolean> asOptionalBoolean()
                                                         throws ConfigMappingException
```
    Maps the node value() to Optional.
    
    Returns:
    
    value as a Optional
    
    Throws:
    
    ConfigMappingException - in case it is not possible map the value
  - asOptionalBooleanSupplier
```
default java.util.function.Supplier<java.util.Optional<java.lang.Boolean>> asOptionalBooleanSupplier()
```
    Returns a supplier to a value typed as an Optional.
    
    Returns:
    
    a supplier to a value typed as an OptionalInt
    
    See Also:
    
    asOptionalBoolean()
  - asOptionalInt
```
default java.util.OptionalInt asOptionalInt()
                                     throws ConfigMappingException
```
    Maps the node value() to OptionalInt.
    
    Returns:
    
    value as a OptionalInt
    
    Throws:
    
    ConfigMappingException - in case it is not possible map the value
  - asOptionalIntSupplier
```
default java.util.function.Supplier<java.util.OptionalInt> asOptionalIntSupplier()
```
    Returns a supplier to a value typed as an OptionalInt.
    
    Returns:
    
    a supplier to a value typed as an OptionalInt
    
    See Also:
    
    asOptionalInt()
  - asOptionalLong
```
default java.util.OptionalLong asOptionalLong()
                                       throws ConfigMappingException
```
    Maps the node value() to OptionalLong.
    
    Returns:
    
    value as a OptionalLong
    
    Throws:
    
    ConfigMappingException - in case it is not possible map the value
  - asOptionalLongSupplier
```
default java.util.function.Supplier<java.util.OptionalLong> asOptionalLongSupplier()
```
    Returns a supplier to a value typed as an OptionalLong.
    
    Returns:
    
    a supplier to a value typed as an OptionalLong
    
    See Also:
    
    asOptionalLong()
  - asOptionalDouble
```
default java.util.OptionalDouble asOptionalDouble()
                                           throws ConfigMappingException
```
    Maps the node value() to OptionalDouble.
    
    Returns:
    
    value as a OptionalDouble
    
    Throws:
    
    ConfigMappingException - in case it is not possible map the value
  - asOptionalDoubleSupplier
```
default java.util.function.Supplier<java.util.OptionalDouble> asOptionalDoubleSupplier()
```
    Returns a supplier to a value typed as an OptionalDouble.
    
    Returns:
    
    a supplier to a value typed as an OptionalDouble
    
    See Also:
    
    asOptionalDouble()
  - mapOptionalList
```
default <T> java.util.Optional<java.util.List<T>> mapOptionalList(java.util.function.Function<java.lang.String,? extends T> mapper)
                                                           throws ConfigMappingException
```
    Returns typed list of type (single values as well as objects) provided by specified type mapper.
    
    Type Parameters:
    
    T - single item type
    
    Parameters:
    
    mapper - type mapper
    
    Returns:
    
    typed list as Optional, empty if entry does not have set value
    
    Throws:
    
    ConfigMappingException - in case of problem to map property value.
  - mapOptionalListSupplier
```
default <T> java.util.function.Supplier<java.util.Optional<java.util.List<T>>> mapOptionalListSupplier(java.util.function.Function<java.lang.String,? extends T> mapper)
```
    Returns a supplier of an optional typed list of a type (single values as well as objects) provided by a specified type mapper.
    
    Type Parameters:
    
    T - single item type
    
    Parameters:
    
    mapper - type mapper
    
    Returns:
    
    a supplier of an optional typed list of a type (single values as well as objects) provided by a specified type mapper
    
    See Also:
    
    mapOptionalList(Function)
  - mapOptionalList
```
default <T> java.util.Optional<java.util.List<T>> mapOptionalList(ConfigMapper<? extends T> mapper)
                                                           throws ConfigMappingException
```
    Returns typed list of type (single values as well as objects) provided by specified type mapper.
    
    Type Parameters:
    
    T - single item type
    
    Parameters:
    
    mapper - type mapper
    
    Returns:
    
    typed list as Optional, empty if entry does not have set value
    
    Throws:
    
    ConfigMappingException - in case of problem to map property value.
  - mapOptionalListSupplier
```
default <T> java.util.function.Supplier<java.util.Optional<java.util.List<T>>> mapOptionalListSupplier(ConfigMapper<? extends T> mapper)
```
    Returns a supplier of an optional typed list of a type (single values as well as objects) provided by a specified type mapper.
    
    Type Parameters:
    
    T - single item type
    
    Parameters:
    
    mapper - type mapper
    
    Returns:
    
    a supplier of an optional typed list of a type (single values as well as objects) provided by a specified type mapper
    
    See Also:
    
    mapOptionalList(ConfigMapper)
  - as
```
default <T> T as(java.lang.Class<? extends T> type)
          throws MissingValueException,
                 ConfigMappingException
```
    Returns typed value as a specified type.
    
    Type Parameters:
    
    T - type
    
    Parameters:
    
    type - type class
    
    Returns:
    
    value as type instance
    
    Throws:
    
    MissingValueException - in case of the missing value for the key represented by this configuration.
    
    ConfigMappingException - in case of problem to map property value.
  - asSupplier
```
default <T> java.util.function.Supplier<T> asSupplier(java.lang.Class<? extends T> type)
```
    Returns a supplier of a typed value.
    
    Type Parameters:
    
    T - type
    
    Parameters:
    
    type - type class
    
    Returns:
    
    a supplier of a typed value
    
    See Also:
    
    as(Class)
  - as
```
default <T> T as(java.lang.Class<? extends T> type,
                 T defaultValue)
          throws ConfigMappingException
```
    Returns typed value as a specified type.
    
    Type Parameters:
    
    T - type
    
    Parameters:
    
    type - type class
    
    defaultValue - default value
    
    Returns:
    
    value as type instance or default value
    
    Throws:
    
    ConfigMappingException - in case of problem to map property value.
  - asSupplier
```
default <T> java.util.function.Supplier<T> asSupplier(java.lang.Class<? extends T> type,
                                                      T defaultValue)
```
    Returns a supplier of a typed value.
    
    Type Parameters:
    
    T - a type
    
    Parameters:
    
    type - a type class
    
    defaultValue - a default value
    
    Returns:
    
    a supplier of a typed value or a default value
    
    See Also:
    
    as(Class, Object)
  - map
```
default <T> T map(java.util.function.Function<java.lang.String,? extends T> mapper)
           throws MissingValueException,
                  ConfigMappingException
```
    Returns typed value as a using specified type mapper.
    
    Type Parameters:
    
    T - type
    
    Parameters:
    
    mapper - type mapper
    
    Returns:
    
    value as type instance
    
    Throws:
    
    MissingValueException - in case of the missing value for the key represented by this configuration.
    
    ConfigMappingException - in case of problem to map property value.
  - mapSupplier
```
default <T> java.util.function.Supplier<T> mapSupplier(java.util.function.Function<java.lang.String,? extends T> mapper)
```
    Returns a supplier of a typed value, using a specified type mapper.
    
    Type Parameters:
    
    T - a type
    
    Parameters:
    
    mapper - a type mapper
    
    Returns:
    
    a supplier of a typed value
    
    See Also:
    
    map(Function)
  - map
```
default <T> T map(ConfigMapper<? extends T> mapper)
           throws MissingValueException,
                  ConfigMappingException
```
    Returns typed value as a using specified config hierarchy mapper.
    
    Type Parameters:
    
    T - type
    
    Parameters:
    
    mapper - config hierarchy mapper
    
    Returns:
    
    value as type instance
    
    Throws:
    
    MissingValueException - in case of the missing value for the key represented by this configuration.
    
    ConfigMappingException - in case of problem to map property value.
  - mapSupplier
```
default <T> java.util.function.Supplier<T> mapSupplier(ConfigMapper<? extends T> mapper)
```
    Returns a supplier of a typed value, using a specified type mapper.
    
    Type Parameters:
    
    T - a type
    
    Parameters:
    
    mapper - a type mapper
    
    Returns:
    
    a supplier of a typed value
    
    See Also:
    
    map(ConfigMapper)
  - map
```
default <T> T map(java.util.function.Function<java.lang.String,? extends T> mapper,
                  T defaultValue)
           throws ConfigMappingException
```
    Returns typed value as a using specified type mapper.
    
    Type Parameters:
    
    T - type
    
    Parameters:
    
    mapper - type mapper
    
    defaultValue - default value
    
    Returns:
    
    value as type instance or default value
    
    Throws:
    
    ConfigMappingException - in case of problem to map property value.
  - mapSupplier
```
default <T> java.util.function.Supplier<T> mapSupplier(java.util.function.Function<java.lang.String,? extends T> mapper,
                                                       T defaultValue)
```
    Returns a supplier of a typed value, using a specified type mapper or a default value.
    
    Type Parameters:
    
    T - a type
    
    Parameters:
    
    mapper - a type mapper
    
    defaultValue - a default value
    
    Returns:
    
    a supplier of a typed value or default value
    
    See Also:
    
    map(Function, Object)
  - map
```
default <T> T map(ConfigMapper<? extends T> mapper,
                  T defaultValue)
           throws ConfigMappingException
```
    Returns typed value as a using specified config hierarchy mapper.
    
    Type Parameters:
    
    T - type
    
    Parameters:
    
    mapper - config hierarchy mapper
    
    defaultValue - default value
    
    Returns:
    
    value as type instance or default value
    
    Throws:
    
    ConfigMappingException - in case of problem to map property value.
  - mapSupplier
```
default <T> java.util.function.Supplier<T> mapSupplier(ConfigMapper<? extends T> mapper,
                                                       T defaultValue)
```
    Returns a supplier of a typed value, using a specified type mapper or a default value.
    
    Type Parameters:
    
    T - a type
    
    Parameters:
    
    mapper - a type mapper
    
    defaultValue - a default value
    
    Returns:
    
    a supplier of a typed value or default value
    
    See Also:
    
    map(ConfigMapper, Object)
  - asList
```
default <T> java.util.List<T> asList(java.lang.Class<? extends T> type)
                              throws MissingValueException,
                                     ConfigMappingException
```
    Returns list of specified type.
    
    Type Parameters:
    
    T - type
    
    Parameters:
    
    type - type class
    
    Returns:
    
    a typed list with values
    
    Throws:
    
    MissingValueException - in case of the missing value for the key represented by this configuration.
    
    ConfigMappingException - in case of problem to map property value.
  - asListSupplier
```
default <T> java.util.function.Supplier<java.util.List<T>> asListSupplier(java.lang.Class<? extends T> type)
```
    Returns a supplier of a list of specified type.
    
    Type Parameters:
    
    T - a type
    
    Parameters:
    
    type - a type class
    
    Returns:
    
    a supplier of a typed list of values
    
    See Also:
    
    asList(Class)
  - asList
```
default <T> java.util.List<T> asList(java.lang.Class<? extends T> type,
                                     java.util.List<T> defaultValue)
                              throws ConfigMappingException
```
    Returns list of specified type.
    
    Type Parameters:
    
    T - type
    
    Parameters:
    
    type - type class
    
    defaultValue - default value
    
    Returns:
    
    a typed list or default value
    
    Throws:
    
    ConfigMappingException - in case of problem to map property value.
  - asListSupplier
```
default <T> java.util.function.Supplier<java.util.List<T>> asListSupplier(java.lang.Class<? extends T> type,
                                                                          java.util.List<T> defaultValue)
```
    Returns a supplier of a list of a specified type or a default value.
    
    Type Parameters:
    
    T - a type
    
    Parameters:
    
    type - a type class
    
    defaultValue - a default value
    
    Returns:
    
    a supplier of a typed list of values or a default value
    
    See Also:
    
    asList(Class, List)
  - mapList
```
default <T> java.util.List<T> mapList(ConfigMapper<? extends T> mapper)
                               throws MissingValueException,
                                      ConfigMappingException
```
    Returns typed list of type provided by specified type mapper.
    
    Type Parameters:
    
    T - mapped Java type
    
    Parameters:
    
    mapper - type mapper
    
    Returns:
    
    a typed list of values or default value
    
    Throws:
    
    MissingValueException - in case of the missing value for the key represented by this configuration.
    
    ConfigMappingException - in case of problem to map property value.
  - mapListSupplier
```
default <T> java.util.function.Supplier<java.util.List<T>> mapListSupplier(ConfigMapper<? extends T> mapper)
```
    Returns a supplier of a list of a type provided by a specified type mapper.
    
    Type Parameters:
    
    T - a type
    
    Parameters:
    
    mapper - a type class
    
    Returns:
    
    a supplier of a list of a type provided by a specified type mapper
    
    See Also:
    
    mapList(ConfigMapper)
  - mapList
```
default <T> java.util.List<T> mapList(ConfigMapper<? extends T> mapper,
                                      java.util.List<T> defaultValue)
                               throws ConfigMappingException
```
    Returns typed list of type provided by specified type mapper.
    
    Type Parameters:
    
    T - mapped Java type
    
    Parameters:
    
    mapper - type mapper
    
    defaultValue - default value
    
    Returns:
    
    a typed list of values or default value
    
    Throws:
    
    ConfigMappingException - in case of problem to map property value.
  - mapListSupplier
```
default <T> java.util.function.Supplier<java.util.List<T>> mapListSupplier(ConfigMapper<? extends T> mapper,
                                                                           java.util.List<T> defaultValue)
```
    Returns a supplier of a list of a type provided by a specified type mapper or a default value.
    
    Type Parameters:
    
    T - a type
    
    Parameters:
    
    mapper - a type class
    
    defaultValue - a default value
    
    Returns:
    
    a supplier of a list of a type provided by a specified type mapper or a default value
    
    See Also:
    
    mapList(ConfigMapper, List)
  - mapList
```
default <T> java.util.List<T> mapList(java.util.function.Function<java.lang.String,? extends T> mapper)
                               throws MissingValueException,
                                      ConfigMappingException
```
    Returns typed list of type provided by specified config hierarchy mapper.
    
    Type Parameters:
    
    T - mapped Java type
    
    Parameters:
    
    mapper - config hierarchy mapper
    
    Returns:
    
    a typed list of values or default value
    
    Throws:
    
    MissingValueException - in case of the missing value for the key represented by this configuration.
    
    ConfigMappingException - in case of problem to map property value.
  - mapListSupplier
```
default <T> java.util.function.Supplier<java.util.List<T>> mapListSupplier(java.util.function.Function<java.lang.String,? extends T> mapper)
```
    Returns a supplier of a list of a type provided by a specified type mapper.
    
    Type Parameters:
    
    T - a type
    
    Parameters:
    
    mapper - a type class
    
    Returns:
    
    a supplier of a list of a type provided by a specified type mapper
    
    See Also:
    
    mapList(Function)
  - mapList
```
default <T> java.util.List<T> mapList(java.util.function.Function<java.lang.String,? extends T> mapper,
                                      java.util.List<T> defaultValue)
                               throws ConfigMappingException
```
    Returns typed list of type provided by specified config hierarchy mapper.
    
    Type Parameters:
    
    T - mapped Java type
    
    Parameters:
    
    mapper - config hierarchy mapper
    
    defaultValue - default value
    
    Returns:
    
    a typed list of values or default value
    
    Throws:
    
    ConfigMappingException - in case of problem to map property value.
  - mapListSupplier
```
default <T> java.util.function.Supplier<java.util.List<T>> mapListSupplier(java.util.function.Function<java.lang.String,? extends T> mapper,
                                                                           java.util.List<T> defaultValue)
```
    Returns a supplier of a list of a type provided by a specified type mapper or a default value.
    
    Type Parameters:
    
    T - a type
    
    Parameters:
    
    mapper - a type class
    
    defaultValue - a default value
    
    Returns:
    
    a supplier of a list of a type provided by a specified type mapper or a default value
    
    See Also:
    
    mapList(Function, List)
  - asString
```
default java.lang.String asString()
                           throws MissingValueException,
                                  ConfigMappingException
```
    Returns a String value of configuration node if the node is Config.Type.VALUE. Throws MissingValueException if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Returns:
    
    single value if the node is Config.Type.VALUE.
    
    Throws:
    
    MissingValueException - in case the node is Config.Type.MISSING.
    
    ConfigMappingException - in case the node is Config.Type.OBJECT or Config.Type.LIST
  - asStringSupplier
```
default java.util.function.Supplier<java.lang.String> asStringSupplier()
```
    Returns a supplier of a String value of this configuration node.
    Calling Supplier.get() returns String value when the node is Config.Type.VALUE. Throws MissingValueException if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Returns:
    
    a supplier of the value if the node is Config.Type.VALUE.
    
    See Also:
    
    asString()
  - asString
```
default java.lang.String asString(java.lang.String defaultValue)
                           throws ConfigMappingException
```
    Returns a String value of configuration node if the node is Config.Type.VALUE. Returns defaultValue if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Parameters:
    
    defaultValue - default value
    
    Returns:
    
    single value if the node is Config.Type.VALUE or defaultValue if the node is Config.Type.MISSING.
    
    Throws:
    
    ConfigMappingException - in case the node is Config.Type.OBJECT or Config.Type.LIST
  - asStringSupplier
```
default java.util.function.Supplier<java.lang.String> asStringSupplier(java.lang.String defaultValue)
```
    Returns a supplier of a String value of this configuration node or a default value.
    Calling Supplier.get() returns String value when the node is Config.Type.VALUE. Returns a defaultValue if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Parameters:
    
    defaultValue - a default value
    
    Returns:
    
    a supplier of the value if the node is Config.Type.VALUE or defaultValue.
    
    See Also:
    
    asString(String)
  - asBoolean
```
default boolean asBoolean()
                   throws MissingValueException,
                          ConfigMappingException
```
    Returns a boolean value of configuration node if the node is Config.Type.VALUE and original value() can be mapped to. Throws MissingValueException if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Returns:
    
    single value if the node is Config.Type.VALUE and can be mapped
    
    Throws:
    
    MissingValueException - in case the node is Config.Type.MISSING.
    
    ConfigMappingException - in case the node is Config.Type.OBJECT or Config.Type.LIST, or value cannot be mapped to.
  - asBooleanSupplier
```
default java.util.function.Supplier<java.lang.Boolean> asBooleanSupplier()
```
    Returns a supplier of a Boolean value of this configuration node.
    Calling Supplier.get() returns Boolean value when the node is Config.Type.VALUE. Throws MissingValueException if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Returns:
    
    a supplier of the value if the node is Config.Type.VALUE.
    
    See Also:
    
    asBoolean()
  - asBoolean
```
default boolean asBoolean(boolean defaultValue)
                   throws ConfigMappingException
```
    Returns a boolean value of configuration node if the node is Config.Type.VALUE and original value() can be mapped to. Returns defaultValue if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Parameters:
    
    defaultValue - a default value
    
    Returns:
    
    single value if the node is Config.Type.VALUE or defaultValue if the node is Config.Type.MISSING.
    
    Throws:
    
    ConfigMappingException - in case the node is Config.Type.OBJECT or Config.Type.LIST, or value cannot be mapped to.
  - asBooleanSupplier
```
default java.util.function.Supplier<java.lang.Boolean> asBooleanSupplier(boolean defaultValue)
```
    Returns a supplier of a Boolean value of this configuration node or a default value.
    Calling Supplier.get() returns Boolean value when the node is Config.Type.VALUE. Returns a defaultValue if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Parameters:
    
    defaultValue - a default value
    
    Returns:
    
    a supplier of the value if the node is Config.Type.VALUE or defaultValue.
    
    See Also:
    
    asBoolean(boolean)
  - asInt
```
default int asInt()
           throws MissingValueException,
                  ConfigMappingException
```
    Returns a int value of configuration node if the node is Config.Type.VALUE and original value() can be mapped to. Throws MissingValueException if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Returns:
    
    single value if the node is Config.Type.VALUE and can be mapped
    
    Throws:
    
    MissingValueException - in case the node is Config.Type.MISSING.
    
    ConfigMappingException - in case the node is Config.Type.OBJECT or Config.Type.LIST, or value cannot be mapped to.
  - asIntSupplier
```
default java.util.function.Supplier<java.lang.Integer> asIntSupplier()
```
    Returns a supplier of a Integer value of this configuration node.
    Calling Supplier.get() returns Integer value when the node is Config.Type.VALUE. Throws MissingValueException if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Returns:
    
    a supplier of the value if the node is Config.Type.VALUE.
    
    See Also:
    
    asInt()
  - asInt
```
default int asInt(int defaultValue)
           throws ConfigMappingException
```
    Returns a int value of configuration node if the node is Config.Type.VALUE and original value() can be mapped to. Returns defaultValue if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Parameters:
    
    defaultValue - a default value
    
    Returns:
    
    single value if the node is Config.Type.VALUE or defaultValue if the node is Config.Type.MISSING.
    
    Throws:
    
    ConfigMappingException - in case the node is Config.Type.OBJECT or Config.Type.LIST, or value cannot be mapped to.
  - asIntSupplier
```
default java.util.function.Supplier<java.lang.Integer> asIntSupplier(int defaultValue)
```
    Returns a supplier of a Integer value of this configuration node or a default value.
    Calling Supplier.get() returns Integer value when the node is Config.Type.VALUE. Returns a defaultValue if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Parameters:
    
    defaultValue - a default value
    
    Returns:
    
    a supplier of the value if the node is Config.Type.VALUE or defaultValue.
    
    See Also:
    
    asInt(int)
  - asLong
```
default long asLong()
             throws MissingValueException,
                    ConfigMappingException
```
    Returns a long value of configuration node if the node is Config.Type.VALUE and original value() can be mapped to. Throws MissingValueException if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Returns:
    
    single value if the node is Config.Type.VALUE and can be mapped
    
    Throws:
    
    MissingValueException - in case the node is Config.Type.MISSING.
    
    ConfigMappingException - in case the node is Config.Type.OBJECT or Config.Type.LIST, or value cannot be mapped to.
  - asLongSupplier
```
default java.util.function.Supplier<java.lang.Long> asLongSupplier()
```
    Returns a supplier of a Long value of this configuration node.
    Calling Supplier.get() returns Long value when the node is Config.Type.VALUE. Throws MissingValueException if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Returns:
    
    a supplier of the value if the node is Config.Type.VALUE.
    
    See Also:
    
    asLong()
  - asLong
```
default long asLong(long defaultValue)
             throws ConfigMappingException
```
    Returns a long value of configuration node if the node is Config.Type.VALUE and original value() can be mapped to. Returns a defaultValue if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Parameters:
    
    defaultValue - a default value
    
    Returns:
    
    single value if the node is Config.Type.VALUE or defaultValue if the node is Config.Type.MISSING.
    
    Throws:
    
    ConfigMappingException - in case the node is Config.Type.OBJECT or Config.Type.LIST, or value cannot be mapped to.
  - asLongSupplier
```
default java.util.function.Supplier<java.lang.Long> asLongSupplier(long defaultValue)
```
    Returns a supplier of a Long value of this configuration node or a default value.
    Calling Supplier.get() returns Long value when the node is Config.Type.VALUE. Returns a defaultValue if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Parameters:
    
    defaultValue - a default value
    
    Returns:
    
    a supplier of the value if the node is Config.Type.VALUE or defaultValue.
    
    See Also:
    
    asLong(long)
  - asDouble
```
default double asDouble()
                 throws MissingValueException,
                        ConfigMappingException
```
    Returns a double value of configuration node if the node is Config.Type.VALUE and original value() can be mapped to. Throws MissingValueException if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Returns:
    
    single value if the node is Config.Type.VALUE and can be mapped
    
    Throws:
    
    MissingValueException - in case the node is Config.Type.MISSING.
    
    ConfigMappingException - in case the node is Config.Type.OBJECT or Config.Type.LIST, or value cannot be mapped to.
  - asDoubleSupplier
```
default java.util.function.Supplier<java.lang.Double> asDoubleSupplier()
```
    Returns a supplier of a Double value of this configuration node.
    Calling Supplier.get() returns Double value when the node is Config.Type.VALUE. Throws MissingValueException if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Returns:
    
    a supplier of the value if the node is Config.Type.VALUE.
    
    See Also:
    
    asDouble()
  - asDouble
```
default double asDouble(double defaultValue)
                 throws ConfigMappingException
```
    Returns a double value of configuration node if the node is Config.Type.VALUE and original value() can be mapped to. Returns a defaultValue if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Parameters:
    
    defaultValue - a default value
    
    Returns:
    
    single value if the node is Config.Type.VALUE or defaultValue if the node is Config.Type.MISSING.
    
    Throws:
    
    ConfigMappingException - in case the node is Config.Type.OBJECT or Config.Type.LIST, or value cannot be mapped to.
  - asDoubleSupplier
```
default java.util.function.Supplier<java.lang.Double> asDoubleSupplier(double defaultValue)
```
    Returns a supplier of a Double value of this configuration node or a default value.
    Calling Supplier.get() returns Double value when the node is Config.Type.VALUE. Returns a defaultValue if the node is Config.Type.MISSING type. Otherwise, if node is Config.Type.OBJECT or Config.Type.LIST, it throws ConfigMappingException.
    
    Parameters:
    
    defaultValue - a default value
    
    Returns:
    
    a supplier of the value if the node is Config.Type.VALUE or defaultValue.
    
    See Also:
    
    asDouble(double)
  - asStringList
```
default java.util.List<java.lang.String> asStringList()
                                               throws MissingValueException,
                                                      ConfigMappingException
```
    Returns a list of Strings mapped from Config.Type.LIST or Config.Type.OBJECT nodes.
    
    Returns:
    
    a list of Strings of it is possible to map elementary sub-nodes into String
    
    Throws:
    
    MissingValueException - in case the node is Config.Type.MISSING.
    
    ConfigMappingException - in case the node is Config.Type.VALUE, or list of nodes cannot be mapped to list of Strings
  - asStringListSupplier
```
default java.util.function.Supplier<java.util.List<java.lang.String>> asStringListSupplier()
```
    Returns a supplier to a list of Strings mapped from Config.Type.LIST or Config.Type.OBJECT nodes.
    Calling Supplier.get() throws MissingValueException if this node is Config.Type.MISSING or ConfigMappingException if this node is Config.Type.VALUE or a list of nodes cannot be mapped to list of Strings.
    
    Returns:
    
    a supplier of a list of Strings of it is possible to map elementary sub-nodes into String
    
    See Also:
    
    asStringList()
  - asStringList
```
default java.util.List<java.lang.String> asStringList(java.util.List<java.lang.String> defaultValue)
                                               throws ConfigMappingException
```
    Returns a list of Strings mapped from Config.Type.LIST or Config.Type.OBJECT nodes. Returns a defaultValue if the node is Config.Type.MISSING type.
    
    Parameters:
    
    defaultValue - a default value
    
    Returns:
    
    a list of Strings of it is possible to map elementary sub-nodes into String or defaultValue if the node is Config.Type.MISSING.
    
    Throws:
    
    ConfigMappingException - in case the node is Config.Type.VALUE, or list of nodes cannot be mapped to list of Strings
  - asStringListSupplier
```
default java.util.function.Supplier<java.util.List<java.lang.String>> asStringListSupplier(java.util.List<java.lang.String> defaultValue)
```
    Returns a supplier to a list of Strings mapped from Config.Type.LIST or Config.Type.OBJECT nodes or a default value.
    Calling Supplier.get() throws ConfigMappingException if this node is Config.Type.VALUE or a list of nodes cannot be mapped to list of Strings.
    
    Parameters:
    
    defaultValue - a default value
    
    Returns:
    
    a supplier of a list of Strings of it is possible to map elementary sub-nodes into String or a defaultValue
    
    See Also:
    
    asStringList(List)
  - asNodeList
```
default java.util.List<Config> asNodeList()
                                   throws MissingValueException,
                                          ConfigMappingException
```
    Returns a list of child Config nodes if the node is Config.Type.OBJECT. Returns a list of element nodes if the node is Config.Type.LIST. Throws MissingValueException if the node is Config.Type.MISSING. Otherwise, if node is Config.Type.VALUE, it throws ConfigMappingException.
    
    Returns:
    
    a list of Config.Type.OBJECT members or a list of Config.Type.LIST members
    
    Throws:
    
    MissingValueException - in case the node is Config.Type.MISSING.
    
    ConfigMappingException - in case the node is Config.Type.VALUE
  - asNodeListSupplier
```
default java.util.function.Supplier<java.util.List<Config>> asNodeListSupplier()
```
    Returns a supplier of a list of child nodes when this node is Config.Type.OBJECT or a list of element nodes for Config.Type.LIST.
    Calling Supplier.get() may throw MissingValueException if this node is Config.Type.MISSING or ConfigMappingException for nodes of type Config.Type.VALUE.
    
    Returns:
    
    a supplier of a list of Config.Type.OBJECT members or a list of Config.Type.LIST members
    
    See Also:
    
    asNodeList()
  - asNodeList
```
default java.util.List<Config> asNodeList(java.util.List<Config> defaultValue)
                                   throws ConfigMappingException
```
    Returns a list of child Config nodes if the node is Config.Type.OBJECT. Returns a list of element nodes if the node is Config.Type.LIST. Returns a defaultValue if the node is Config.Type.MISSING. Otherwise, if node is Config.Type.VALUE, it throws ConfigMappingException.
    
    Parameters:
    
    defaultValue - a default value
    
    Returns:
    
    list of Config.Type.OBJECT members, list of Config.Type.LIST members or defaultValue in case of Config.Type.MISSING
    
    Throws:
    
    ConfigMappingException - in case the node is Config.Type.VALUE
  - asNodeListSupplier
```
default java.util.function.Supplier<java.util.List<Config>> asNodeListSupplier(java.util.List<Config> defaultValue)
```
    Returns a supplier of a list of child nodes when this node is Config.Type.OBJECT, a list of element nodes for Config.Type.LIST or defaultValue if this node is Config.Type.MISSING.
    Calling Supplier.get() may throw ConfigMappingException for nodes of type Config.Type.VALUE.
    
    Parameters:
    
    defaultValue - a default value
    
    Returns:
    
    a supplier of a list of Config.Type.OBJECT members or a list of Config.Type.LIST members or defaultValue in case of Config.Type.MISSING
    
    See Also:
    
    asNodeList(List)
  - asMap
```
default java.util.Map<java.lang.String,java.lang.String> asMap()
                                                        throws MissingValueException
```
    Transform all leaf nodes (values) into Map instance.
    Fully qualified key of config node is used as a key in returned Map. Detach config node before transforming to Map in case you want to cut current Config node key prefix.
    Let's say we work with following configuration:
```
 app:
      name: Example 1
      page-size: 20
 logging:
      app.level = INFO
      level = WARNING
 
```
    Map app1 contains two keys: app.name, app.page-size.
```
 Map<String, String> app1 = config.get("app").asMap();
 
```
    Detaching app config node returns new Config instance with "reset" local root.
```
 Map<String, String> app2 = config.get("app").detach().asMap();
 
```
    Map app2 contains two keys without app prefix: name, page-size.
    Returns:
    
    new Map instance that contains all config leaf node values
    
    Throws:
    
    MissingValueException - in case the node is Config.Type.MISSING.
    
    See Also:
    
    asOptionalMap(), asMap(Map), traverse(), detach()
  - asMapSupplier
```
default java.util.function.Supplier<java.util.Map<java.lang.String,java.lang.String>> asMapSupplier()
```
    Returns a supplier of a map with transformed leaf nodes.
    For detail see asMap().
    
    Returns:
    
    a supplier of a map with transformed leaf nodes
    
    See Also:
    
    asMap()
  - asMap
```
default java.util.Map<java.lang.String,java.lang.String> asMap(java.util.Map<java.lang.String,java.lang.String> defaultValue)
```
    Transform all leaf nodes (values) into Map instance.
    Fully qualified key of config node is used as a key in returned Map. Detach config node before transforming to Map in case you want to cut current Config node key prefix.
    Let's say we work with following configuration:
```
 app:
      name: Example 1
      page-size: 20
 logging:
      app.level = INFO
      level = WARNING
 
```
    Map app1 contains two keys: app.name, app.page-size.
```
 Map<String, String> app1 = config.get("app").asMap(CollectionsHelper.mapOf());
 
```
    Detaching app config node returns new Config instance with "reset" local root.
```
 Map<String, String> app2 = config.get("app").detach().asMap(CollectionsHelper.mapOf());
 
```
    Map app2 contains two keys without app prefix: name, page-size.
    Parameters:
    
    defaultValue - a default value
    
    Returns:
    
    new Map instance that contains all config leaf node values or defaultValue in case of Config.Type.MISSING
    
    See Also:
    
    asOptionalMap(), asMap(), traverse(), detach()
  - asMapSupplier
```
default java.util.function.Supplier<java.util.Map<java.lang.String,java.lang.String>> asMapSupplier(java.util.Map<java.lang.String,java.lang.String> defaultValue)
```
    Returns a supplier of a map with transformed leaf nodes or a default value if this node is Config.Type.MISSING.
    For detail see asMap(Map).
    
    Parameters:
    
    defaultValue - a default value
    
    Returns:
    
    a supplier of a map with transformed leaf nodes
    
    See Also:
    
    asMap(Map)
  - changes
```
@Deprecated
default io.helidon.common.reactive.Flow.Publisher<Config> changes()
```
    Deprecated.
    
    Allows to subscribe on change on whole Config as well as on particular Config node.
    A user can subscribe on root Config node and than will be notified on any change of Configuration. You can also subscribe on any sub-node, i.e. you will receive notification events just about sub-configuration. No matter how much the sub-configuration has changed you will receive just one notification event that is associated with a node you are subscribed on. If a user subscribes on older instance of Config and ones has already been published the last one is automatically submitted to new-subscriber.
    The Config notification support is based on ConfigSource changes support.
    Method Flow.Subscriber.onError(Throwable) is never called. Method Flow.Subscriber.onComplete() is called in case an associated ConfigSource's changes Publisher signals onComplete as well.
    Note: It does not matter what instance version of Config (related to single Config.Builder initialization) a user subscribes on. It is enough to subscribe just on single (e.g. on the first) Config instance. There is no added value to subscribe again on new Config instance.
    
    Returns:
    
    Flow.Publisher to be subscribed in. Never returns null.
    
    See Also:
    
    onChange(Function)
  - onChange
```
default void onChange(java.util.function.Function<Config,java.lang.Boolean> onNextFunction)
```
    Directly subscribes onNextFunction function on change on whole Config or on particular Config node.
    It automatically creates Flow.Subscriber that will delegate Flow.Subscriber.onNext(Object) to specified onNextFunction function. Created subscriber automatically requests all events in it's Flow.Subscriber.onSubscribe(Flow.Subscription) method. Function onNextFunction returns false in case user wants to cancel current subscription.
    A user can subscribe on root Config node and than will be notified on any change of Configuration. You can also subscribe on any sub-node, i.e. you will receive notification events just about sub-configuration. No matter how much the sub-configuration has changed you will receive just one notification event that is associated with a node you are subscribed on. If a user subscribes on older instance of Config and ones has already been published the last one is automatically submitted to new-subscriber.
    The Config notification support is based on ConfigSource changes support.
    Note: It does not matter what instance version of Config (related to single Config.Builder initialization) a user subscribes on. It is enough to subscribe just on single (e.g. on the first) Config instance. There is no added value to subscribe again on new Config instance.
    
    Parameters:
    
    onNextFunction - Flow.Subscriber.onNext(Object) functionality
    
    See Also:
    
    changes(), ConfigHelper.subscriber(Function)

Interface Config

Loading Configuration

Navigating in a Configuration Tree

Converting Configuration Values to Types

Explicit Conversion by the Application

Using Built-in and Custom Mappers

Handling Multiple Configuration Sources

Nested Class Summary

Method Summary

Method Detail

empty

create

from

loadSourcesFrom

withSources

loadSources

builder

context

timestamp

key

name

get

get

detach

type

exists

isLeaf

hasValue

ifExists

ifExistsOrElse

traverse

traverse

value

asOptionalString

asOptionalStringSupplier

node

nodeSupplier

nodeList

asOptionalNodeList

asOptionalNodeListSupplier

asOptionalMap

asOptionalMapSupplier

asOptional

asOptionalSupplier

asOptionalList

asOptionalListSupplier

asOptionalStringList

asOptionalStringListSupplier

mapOptional

mapOptionalSupplier

mapOptional

mapOptionalSupplier

asOptionalBoolean

asOptionalBooleanSupplier

asOptionalInt

asOptionalIntSupplier

asOptionalLong

asOptionalLongSupplier

asOptionalDouble

asOptionalDoubleSupplier

mapOptionalList

mapOptionalListSupplier

mapOptionalList

mapOptionalListSupplier

as

asSupplier

as

asSupplier

map

mapSupplier

map

mapSupplier

map

mapSupplier

map

mapSupplier

asList

asListSupplier

asList

asListSupplier