ArgumentHint (Flink : Table : Common 2.1.0 API)

```
@PublicEvolving
@Retention(RUNTIME)
@Target({TYPE,METHOD,FIELD,PARAMETER})
public @interface ArgumentHint
```
A hint that provides additional information about an argument.
An ArgumentHint can be used to provide hints about the name, optionality, and data type of argument.
For example, @ArgumentHint(name = "in1", type = @DataTypeHint("STRING"), isOptional = false) is a scalar argument with the data type STRING, named "in1", and cannot be omitted when calling.

See Also:

FunctionHint

Optional Element Summary

Optional Elements
Modifier and Type	Optional Element	Description
`boolean`	`isOptional`	Specifies whether the argument is optional or required.
`String`	`name`	The name of the argument.
`DataTypeHint`	`type`	The data type hint for the argument.
`ArgumentTrait[]`	`value`	The kind of the argument.

- Element Detail
  - value
```
ArgumentTrait[] value
```
    The kind of the argument.
    Only applies to ProcessTableFunctions (PTFs). Others can only take scalar values.
    
    Default:
    
    {org.apache.flink.table.annotation.ArgumentTrait.SCALAR}
- - name
```
String name
```
    The name of the argument. It must be unique among other arguments.
    This can be used to provide a descriptive name for the argument.
    
    Default:
    
    ""
- - isOptional
```
boolean isOptional
```
    Specifies whether the argument is optional or required.
    If set to true, the argument is considered optional.And if the user does not specify this parameter when calling, 'null' will be passed in. By default, an argument is considered required.
    
    Default:
    
    false
- - type
```
DataTypeHint type
```
    The data type hint for the argument.
    This can be used to provide additional information about the expected data type of the argument. The DataTypeHint annotation can be used to specify the data type explicitly or provide hints for the reflection-based extraction of the data type.
    
    Default:
    
    @org.apache.flink.table.annotation.DataTypeHint