CloseableIteratorWithMetadata (druid-processing 28.0.1 API)

All Superinterfaces:

AutoCloseable, Closeable, CloseableIterator<T>, Iterator<T>
```
public interface CloseableIteratorWithMetadata<T>
extends CloseableIterator<T>
```
Like CloseableIterator, but has a currentMetadata() method, which returns "metadata", which is effectively a Map about the source of last value returned by next() The returned metadata is read-only and cannot be modified. This metadata can be used as additional information to pin-point the root cause of a parse exception. So it can include information that helps with such exercise. For example, for a TextReader that information can be the line number. Only per row context needs to be passed here so for kafka it could be an offset. The source information is already available via IntermediateRowParsingReader.source() method and needn't be included

Method Summary

All Methods Static Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`Map<String,Object>`	`currentMetadata()`
`static <T> CloseableIteratorWithMetadata<T>`	`withEmptyMetadata(CloseableIterator<T> delegate)`	Creates an instance of CloseableIteratorWithMetadata from a `CloseableIterator`.

Methods inherited from interface java.io.Closeable
close

Methods inherited from interface org.apache.druid.java.util.common.parsers.CloseableIterator
flatMap, map

Methods inherited from interface java.util.Iterator
forEachRemaining, hasNext, next, remove

- Method Detail
  - currentMetadata
```
Map<String,Object> currentMetadata()
```
    Returns:
    
    A map containing the information about the source of the last value returned by Iterator.next()
  - withEmptyMetadata
```
static <T> CloseableIteratorWithMetadata<T> withEmptyMetadata(CloseableIterator<T> delegate)
```
    Creates an instance of CloseableIteratorWithMetadata from a CloseableIterator. currentMetadata() for the instance is guaranteed to return an empty map