Polish 117b7d5

* Update year in license headers
* Add/Amend Javadocs
* Update assertion message to be consistent between the writer and its builder

Author: fmbenhassine

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2018 the original author or authors.
+ * Copyright 2020 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.
@@ -25,22 +25,42 @@
 
 /**
  * An {@link ItemStreamWriter} decorator with a synchronized
- * {@link SynchronizedItemStreamWriter#write write()} method
+ * {@link SynchronizedItemStreamWriter#write write()} method.
+ * 
+ * This decorator is useful when using a non thread-safe item writer
+ * in a multi-threaded step. Typical delegate examples are the
+ * {@link org.springframework.batch.item.json.JsonFileItemWriter JsonFileItemWriter}
+ * and {@link org.springframework.batch.item.xml.StaxEventItemWriter StaxEventItemWriter}.
+ * 
+ * <p>
+ * <strong>It should be noted that synchronizing writes might introduce
+ * some performance degradation, so this decorator should be used
+ * wisely and only when necessary. For example, using a 
+ * {@link org.springframework.batch.item.file.FlatFileItemWriter FlatFileItemWriter} in
+ * a multi-threaded step does NOT require synchronizing writes, so using
+ * this decorator in such use case might be counter-productive.</strong>
+ * </p>
  *
  * @author Dimitrios Liapis
+ * @author Mahmoud Ben Hassine
  *
  * @param <T> type of object being written
  */
 public class SynchronizedItemStreamWriter<T> implements ItemStreamWriter<T>, InitializingBean {
 
 	private ItemStreamWriter<T> delegate;
 
+	/**
+	 * Set the delegate {@link ItemStreamWriter}.
+	 * 
+	 * @param delegate the delegate to set
+	 */
 	public void setDelegate(ItemStreamWriter<T> delegate) {
 		this.delegate = delegate;
 	}
 
 	/**
-	 * This delegates to the write method of the <code>delegate</code>
+	 * This method delegates to the {@code write} method of the {@code delegate}.
 	 */
 	@Override
 	public synchronized void write(List<? extends T> items) throws Exception {

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2018 the original author or authors.
+ * Copyright 2020 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.
@@ -23,19 +23,31 @@
  * Creates a fully qualified {@link SynchronizedItemStreamWriter}.
  *
  * @author Dimitrios Liapis
+ * @author Mahmoud Ben Hassine
  */
 public class SynchronizedItemStreamWriterBuilder<T> {
 
 	private ItemStreamWriter<T> delegate;
 
+	/**
+	 * Set the delegate {@link ItemStreamWriter}.
+	 * 
+	 * @param delegate the delegate to set
+	 * @return this instance for method chaining
+	 */
 	public SynchronizedItemStreamWriterBuilder<T> delegate(ItemStreamWriter<T> delegate) {
 		this.delegate = delegate;
 
 		return this;
 	}
 
+	/**
+	 * Returns a fully constructed {@link SynchronizedItemStreamWriter}.
+	 * 
+	 * @return a new {@link SynchronizedItemStreamWriter}
+	 */
 	public SynchronizedItemStreamWriter<T> build() {
-		Assert.notNull(this.delegate, "A delegate is required");
+		Assert.notNull(this.delegate, "A delegate item writer is required");
 
 		SynchronizedItemStreamWriter<T> writer = new SynchronizedItemStreamWriter<>();
 		writer.setDelegate(this.delegate);

spring-batch-infrastructure/src/test/java/org/springframework/batch/item/support/AbstractSynchronizedItemStreamWriterTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2018 the original author or authors.
+ * Copyright 2020 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.

spring-batch-infrastructure/src/test/java/org/springframework/batch/item/support/SynchronizedItemStreamWriterTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2018 the original author or authors.
+ * Copyright 2020 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.

spring-batch-infrastructure/src/test/java/org/springframework/batch/item/support/builder/SynchronizedItemStreamWriterBuilderTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2018 the original author or authors.
+ * Copyright 2020 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.
@@ -37,7 +37,7 @@ protected SynchronizedItemStreamWriter<Object> createNewSynchronizedItemStreamWr
 	@Test
 	public void testBuilderDelegateIsNotNull() {
 		expectedException.expect(IllegalArgumentException.class);
-		expectedException.expectMessage("A delegate is required");
+		expectedException.expectMessage("A delegate item writer is required");
 		new SynchronizedItemStreamWriterBuilder<>().build();
 	}
 }