Introduce ErrorProne, fix compiler warnings

Signed-off-by: Stefano Cordio <[email protected]>

Author: scordio

Diff for: .mvn/jvm.config

@@ -0,0 +1,10 @@
+--add-exports jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.model=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.processing=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED
+--add-opens jdk.compiler/com.sun.tools.javac.code=ALL-UNNAMED
+--add-opens jdk.compiler/com.sun.tools.javac.comp=ALL-UNNAMED

Diff for: pom.xml

@@ -180,7 +180,19 @@
 					<release>${java.version}</release>
 					<compilerArgs>
 						<compilerArg>-parameters</compilerArg>
+						<!-- https://errorprone.info/docs/installation#maven -->
+						<compilerArg>-XDcompilePolicy=simple</compilerArg>
+						<compilerArg>--should-stop=ifError=FLOW</compilerArg>
+						<compilerArg>-Xplugin:ErrorProne -Xep:NonAtomicVolatileUpdate:OFF</compilerArg>
 					</compilerArgs>
+					<failOnWarning>true</failOnWarning>
+					<annotationProcessorPaths>
+						<path>
+							<groupId>com.google.errorprone</groupId>
+							<artifactId>error_prone_core</artifactId>
+							<version>2.37.0</version>
+						</path>
+					</annotationProcessorPaths>
 				</configuration>
 			</plugin>
 			<plugin>

Diff for: spring-batch-core/src/test/java/org/springframework/batch/core/listener/CompositeItemReadListenerTests.java

@@ -17,7 +17,7 @@
 
 import static org.mockito.Mockito.mock;
 
-import java.util.ArrayList;
+import java.util.List;
 
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -67,11 +67,7 @@ void testOnReadError() {
 
 	@Test
 	void testSetListeners() {
-		compositeListener.setListeners(new ArrayList<>() {
-			{
-				add(listener);
-			}
-		});
+		compositeListener.setListeners(List.of(listener));
 		listener.beforeRead();
 		compositeListener.beforeRead();
 	}

Diff for: spring-batch-core/src/test/java/org/springframework/batch/core/listener/CompositeItemWriteListenerTests.java

@@ -15,7 +15,7 @@
  */
 package org.springframework.batch.core.listener;
 
-import java.util.ArrayList;
+import java.util.List;
 
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -69,11 +69,7 @@ void testOnWriteError() {
 
 	@Test
 	void testSetListeners() {
-		compositeListener.setListeners(new ArrayList<>() {
-			{
-				add(listener);
-			}
-		});
+		compositeListener.setListeners(List.of(listener));
 		Chunk<Object> item = Chunk.of(new Object());
 		listener.beforeWrite(item);
 		compositeListener.beforeWrite(item);

Diff for: spring-batch-core/src/test/java/org/springframework/batch/core/step/tasklet/ConfigurableSystemProcessExitCodeMapperTests.java

@@ -36,16 +36,13 @@ class ConfigurableSystemProcessExitCodeMapperTests {
 	 */
 	@Test
 	void testMapping() {
-		Map<Object, ExitStatus> mappings = new HashMap<>() {
-			{
-				put(0, ExitStatus.COMPLETED);
-				put(1, ExitStatus.FAILED);
-				put(2, ExitStatus.EXECUTING);
-				put(3, ExitStatus.NOOP);
-				put(4, ExitStatus.UNKNOWN);
-				put(ConfigurableSystemProcessExitCodeMapper.ELSE_KEY, ExitStatus.UNKNOWN);
-			}
-		};
+		Map<Object, ExitStatus> mappings = Map.of( //
+				0, ExitStatus.COMPLETED, //
+				1, ExitStatus.FAILED, //
+				2, ExitStatus.EXECUTING, //
+				3, ExitStatus.NOOP, //
+				4, ExitStatus.UNKNOWN, //
+				ConfigurableSystemProcessExitCodeMapper.ELSE_KEY, ExitStatus.UNKNOWN);
 
 		mapper.setMappings(mappings);
 

Diff for: spring-batch-infrastructure/src/main/java/org/springframework/batch/item/Chunk.java

@@ -26,7 +26,7 @@
 
 /**
  * Encapsulation of a list of items to be processed and possibly a list of failed items to
- * be skipped. To mark an item as skipped clients should iterate over the chunk using the
+ * be skipped. To mark an item as skipped, clients should iterate over the chunk using the
  * {@link #iterator()} method, and if there is a failure call
  * {@link Chunk.ChunkIterator#remove()} on the iterator. The skipped items are then
  * available through the chunk.
@@ -100,21 +100,21 @@ public void clear() {
 	}
 
 	/**
-	 * @return a copy of the items to be processed as an unmodifiable list
+	 * Return a copy of the items to be processed as an unmodifiable list.
 	 */
 	public List<W> getItems() {
 		return Collections.unmodifiableList(items);
 	}
 
 	/**
-	 * @return a copy of the skips as an unmodifiable list
+	 * Return a copy of the skips as an unmodifiable list.
 	 */
 	public List<SkipWrapper<W>> getSkips() {
 		return Collections.unmodifiableList(skips);
 	}
 
 	/**
-	 * @return a copy of the anonymous errors as an unmodifiable list
+	 * Return a copy of the anonymous errors as an unmodifiable list.
 	 */
 	public List<Exception> getErrors() {
 		return Collections.unmodifiableList(errors);
@@ -130,7 +130,7 @@ public void skip(Exception e) {
 	}
 
 	/**
-	 * @return true if there are no items in the chunk
+	 * Return {@code true} if there are no items in the chunk.
 	 */
 	public boolean isEmpty() {
 		return items.isEmpty();
@@ -146,7 +146,7 @@ public ChunkIterator iterator() {
 	}
 
 	/**
-	 * @return the number of items (excluding skips)
+	 * Returns the number of items (excluding skips).
 	 */
 	public int size() {
 		return items.size();

Diff for: spring-batch-infrastructure/src/main/java/org/springframework/batch/item/adapter/AbstractMethodInvokingDelegator.java

@@ -29,9 +29,9 @@
 import org.springframework.util.StringUtils;
 
 /**
- * Superclass for delegating classes which dynamically call a custom method of injected
- * object. Provides convenient API for dynamic method invocation shielding subclasses from
- * low-level details and exception handling.
+ * Superclass for delegating classes which dynamically call a custom method of an injected
+ * object. Provides a convenient API for dynamic method invocation shielding subclasses
+ * from low-level details and exception handling.
  * <p>
  * {@link Exception}s thrown by a successfully invoked delegate method are re-thrown
  * without wrapping. In case the delegate method throws a {@link Throwable} that doesn't
@@ -164,7 +164,7 @@ private boolean targetClassDeclaresTargetMethod() {
 						if (arguments[j] == null) {
 							continue;
 						}
-						if (!(ClassUtils.isAssignableValue(params[j], arguments[j]))) {
+						if (!ClassUtils.isAssignableValue(params[j], arguments[j])) {
 							argumentsMatchParameters = false;
 						}
 					}
@@ -179,24 +179,23 @@ private boolean targetClassDeclaresTargetMethod() {
 	}
 
 	/**
-	 * @param targetObject the delegate - bean id can be used to set this value in Spring
-	 * configuration
+	 * Set the delegate - bean id can be used to set this value in Spring configuration.
 	 */
 	public void setTargetObject(Object targetObject) {
 		this.targetObject = targetObject;
 	}
 
 	/**
-	 * @param targetMethod name of the method to be invoked on
-	 * {@link #setTargetObject(Object)}.
+	 * Set the name of the method to be invoked on {@link #setTargetObject(Object)}.
 	 */
 	public void setTargetMethod(String targetMethod) {
 		this.targetMethod = targetMethod;
 	}
 
 	/**
-	 * @param arguments arguments values for the { {@link #setTargetMethod(String)}. These
-	 * will be used only when the subclass tries to invoke the target method without
+	 * Set the argument values for the {@link #setTargetMethod(String)}.
+	 * <p>
+	 * These will be used only when the subclass tries to invoke the target method without
 	 * providing explicit argument values.
 	 * <p>
 	 * If arguments are set to not-null value {@link #afterPropertiesSet()} will check the
@@ -205,27 +204,26 @@ public void setTargetMethod(String targetMethod) {
 	 * will be supplied at runtime.
 	 */
 	public void setArguments(Object[] arguments) {
-		this.arguments = arguments == null ? null : Arrays.asList(arguments).toArray();
+		this.arguments = arguments == null ? null : arguments.clone();
 	}
 
 	/**
-	 * Return arguments.
-	 * @return arguments
+	 * Return the argument values for the method to be invoked.
 	 */
 	protected Object[] getArguments() {
 		return arguments;
 	}
 
 	/**
-	 * @return the object on which the method will be invoked.
+	 * Return the object on which the method will be invoked.
 	 * @since 5.1
 	 */
 	protected Object getTargetObject() {
 		return targetObject;
 	}
 
 	/**
-	 * @return the name of the method to be invoked.
+	 * Return the name of the method to be invoked.
 	 * @since 5.1
 	 */
 	protected String getTargetMethod() {

Diff for: spring-batch-infrastructure/src/main/java/org/springframework/batch/item/adapter/PropertyExtractingDelegatingItemWriter.java

@@ -72,13 +72,13 @@ public void afterPropertiesSet() throws Exception {
 	}
 
 	/**
-	 * @param fieldsUsedAsMethodArguments the values of the these item's fields will be
-	 * used as arguments for the delegate method. Nested property values are supported,
-	 * e.g. <code>address.city</code>
+	 * Sets the values of the item's fields to be used as arguments for the delegate
+	 * method.
+	 * <p>
+	 * Nested property values are supported, e.g. <code>address.city</code>
 	 */
 	public void setFieldsUsedAsTargetMethodArguments(String[] fieldsUsedAsMethodArguments) {
-		this.fieldsUsedAsTargetMethodArguments = Arrays.asList(fieldsUsedAsMethodArguments)
-			.toArray(new String[fieldsUsedAsMethodArguments.length]);
+		this.fieldsUsedAsTargetMethodArguments = fieldsUsedAsMethodArguments.clone();
 	}
 
 }

Diff for: spring-batch-infrastructure/src/main/java/org/springframework/batch/item/avro/builder/AvroItemReaderBuilder.java

@@ -24,6 +24,8 @@
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
+import java.nio.charset.Charset;
+
 /**
  * A builder implementation for the {@link AvroItemReader}.
  *
@@ -80,7 +82,7 @@ public AvroItemReaderBuilder<T> schema(Resource schema) {
 	 */
 	public AvroItemReaderBuilder<T> schema(String schemaString) {
 		Assert.hasText(schemaString, "A 'schema' is required.");
-		this.schema = new ByteArrayResource(schemaString.getBytes());
+		this.schema = new ByteArrayResource(schemaString.getBytes(Charset.defaultCharset()));
 		return this;
 	}
 

Diff for: spring-batch-infrastructure/src/main/java/org/springframework/batch/item/avro/builder/AvroItemWriterBuilder.java

@@ -22,6 +22,8 @@
 import org.springframework.core.io.WritableResource;
 import org.springframework.util.Assert;
 
+import java.nio.charset.Charset;
+
 /**
  * A builder implementation for the {@link AvroItemWriter}.
  *
@@ -40,7 +42,8 @@ public class AvroItemWriterBuilder<T> {
 	private String name = AvroItemWriter.class.getSimpleName();
 
 	/**
-	 * @param resource the {@link WritableResource} used to write the serialized data.
+	 * Sets the {@link WritableResource} used to write the serialized data.
+	 * @param resource the {@code WritableResource} used to write the serialized data.
 	 * @return The current instance of the builder.
 	 */
 	public AvroItemWriterBuilder<T> resource(WritableResource resource) {
@@ -50,7 +53,9 @@ public AvroItemWriterBuilder<T> resource(WritableResource resource) {
 	}
 
 	/**
-	 * @param schema the Resource containing the schema JSON used to serialize the output.
+	 * Sets the {@link Resource} containing the schema JSON used to serialize the output.
+	 * @param schema the {@code Resource} containing the schema JSON used to serialize the
+	 * output.
 	 * @return The current instance of the builder.
 	 */
 	public AvroItemWriterBuilder<T> schema(Resource schema) {
@@ -61,17 +66,19 @@ public AvroItemWriterBuilder<T> schema(Resource schema) {
 	}
 
 	/**
+	 * Sets the String containing the schema JSON used to serialize the output.
 	 * @param schemaString the String containing the schema JSON used to serialize the
 	 * output.
 	 * @return The current instance of the builder.
 	 */
 	public AvroItemWriterBuilder<T> schema(String schemaString) {
 		Assert.hasText(schemaString, "A 'schemaString' is required.");
-		this.schema = new ByteArrayResource(schemaString.getBytes());
+		this.schema = new ByteArrayResource(schemaString.getBytes(Charset.defaultCharset()));
 		return this;
 	}
 
 	/**
+	 * Sets the Class of objects to be serialized.
 	 * @param type the Class of objects to be serialized.
 	 * @return The current instance of the builder.
 	 */

Diff for: spring-batch-infrastructure/src/main/java/org/springframework/batch/item/data/MongoCursorItemReader.java

@@ -101,7 +101,7 @@ public void setTargetType(Class<? extends T> targetType) {
 	}
 
 	/**
-	 * @param collection Mongo collection to be queried.
+	 * The Mongo collection to be queried.
 	 */
 	public void setCollection(String collection) {
 		this.collection = collection;

Diff for: spring-batch-infrastructure/src/main/java/org/springframework/batch/item/data/MongoItemReader.java

@@ -172,7 +172,7 @@ public void setSort(Map<String, Sort.Direction> sorts) {
 	}
 
 	/**
-	 * @param collection Mongo collection to be queried.
+	 * The Mongo collection to be queried.
 	 */
 	public void setCollection(String collection) {
 		this.collection = collection;

Diff for: spring-batch-infrastructure/src/main/java/org/springframework/batch/item/data/MongoItemWriter.java

@@ -107,7 +107,7 @@ public MongoItemWriter() {
 	 */
 	@Deprecated(since = "5.1", forRemoval = true)
 	public void setDelete(boolean delete) {
-		this.mode = (delete) ? Mode.REMOVE : Mode.UPSERT;
+		this.mode = delete ? Mode.REMOVE : Mode.UPSERT;
 	}
 
 	/**

Diff for: spring-batch-infrastructure/src/main/java/org/springframework/batch/item/data/MongoPagingItemReader.java

@@ -67,6 +67,7 @@
  * @author Mahmoud Ben Hassine
  * @author Parikshit Dutta
  */
+@SuppressWarnings("removal")
 public class MongoPagingItemReader<T> extends MongoItemReader<T> {
 
 	/**

Diff for: spring-batch-infrastructure/src/main/java/org/springframework/batch/item/data/RepositoryItemReader.java

@@ -44,7 +44,7 @@
 /**
  * <p>
  * A {@link org.springframework.batch.item.ItemReader} that reads records utilizing a
- * {@link org.springframework.data.repository.PagingAndSortingRepository}.
+ * {@link PagingAndSortingRepository}.
  * </p>
  *
  * <p>
@@ -55,7 +55,7 @@
  *
  * <p>
  * The reader must be configured with a
- * {@link org.springframework.data.repository.PagingAndSortingRepository}, a
+ * {@link PagingAndSortingRepository}, a
  * {@link org.springframework.data.domain.Sort}, and a pageSize greater than 0.
  * </p>
  *
@@ -127,15 +127,14 @@ public void setSort(Map<String, Sort.Direction> sorts) {
 	}
 
 	/**
-	 * @param pageSize The number of items to retrieve per page. Must be greater than 0.
+	 * The number of items to retrieve per page. Must be greater than 0.
 	 */
 	public void setPageSize(int pageSize) {
 		this.pageSize = pageSize;
 	}
 
 	/**
-	 * The {@link org.springframework.data.repository.PagingAndSortingRepository}
-	 * implementation used to read input from.
+	 * The {@link PagingAndSortingRepository} implementation used to read input from.
 	 * @param repository underlying repository for input to be read from.
 	 */
 	public void setRepository(PagingAndSortingRepository<?, ?> repository) {