Clarify the behaviour of MultiResourceItemWriter with regard to file creation

Resolves #4645

Author: fmbenhassine

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/file/MultiResourceItemWriter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006-2023 the original author or authors.
+ * Copyright 2006-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -36,7 +36,11 @@
  * <p>
  * Note that new resources are created only at chunk boundaries i.e. the number of items
  * written into one resource is between the limit set by
- * {@link #setItemCountLimitPerResource(int)} and (limit + chunk size).
+ * <p>
+ * This writer will create an output file only when there are items to write, which means
+ * there would be no empty file created if no items are passed (for example when all items
+ * are filtered or skipped during the processing phase).
+ * </p>
  *
  * @param <T> item type
  * @author Robert Kasanicky