Update Javadocs about exception handling when closing composite streams

Related to #4764 and #4750

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/support/CompositeItemReader.java

@@ -79,6 +79,12 @@ public class CompositeItemReader<T> implements ItemStreamReader<T> {
 		}
 	}
 
+	/**
+	 * Close all delegates.
+	 * @throws ItemStreamException thrown if one of the delegates fails to close. Original
+	 * exceptions thrown by delegates are added as suppressed exceptions into this one, in
+	 * the same order as delegates were registered.
+	 */
 	@Override
 	public void close() throws ItemStreamException {
 		List<Exception> exceptions = new ArrayList<>();

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/support/CompositeItemStream.java

@@ -102,7 +102,8 @@ public class CompositeItemStream implements ItemStream {
 	/**
 	 * Broadcast the call to close.
 	 * @throws ItemStreamException thrown if one of the {@link ItemStream}s in the list
-	 * fails to close.
+	 * fails to close. Original exceptions thrown by delegates are added as suppressed
+	 * exceptions into this one, in the same order as delegates were registered.
 	 */
 	@Override
 	public void close() throws ItemStreamException {

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/support/CompositeItemWriter.java

@@ -105,6 +105,12 @@ public class CompositeItemWriter<T> implements ItemStreamWriter<T>, Initializing
 		this.delegates = delegates;
 	}
 
+	/**
+	 * Close all delegates.
+	 * @throws ItemStreamException thrown if one of the delegates fails to close. Original
+	 * exceptions thrown by delegates are added as suppressed exceptions into this one, in
+	 * the same order as delegates were registered.
+	 */
 	@Override
 	public void close() throws ItemStreamException {
 		List<Exception> exceptions = new ArrayList<>();