Migrate spring-batch-infrastructure to JSpecify annotations

pom.xml

@@ -148,7 +148,8 @@
 		<maven-assembly-plugin.version>3.7.1</maven-assembly-plugin.version>
 		<maven-jar-plugin.version>3.4.2</maven-jar-plugin.version>
 		<spring-javaformat-maven-plugin.version>0.0.47</spring-javaformat-maven-plugin.version>
-		<error-prone.version>2.41.0</error-prone.version>
+		<error-prone.version>2.42.0</error-prone.version>
+		<nullaway.version>0.12.10</nullaway.version>
 	</properties>
 
 	<build>
@@ -180,6 +181,14 @@
 						<compilerArg>--should-stop=ifError=FLOW</compilerArg>
 						<compilerArg>
 							-Xplugin:ErrorProne
+							<!-- Check JSpecify annotations -->
+							-Xep:NullAway:ERROR
+							-XepOpt:NullAway:OnlyNullMarked
+							<!-- FIXME Remove once https://github.com/uber/NullAway/pull/1295 is released -->
+							-XepOpt:NullAway:CustomContractAnnotations=org.springframework.lang.Contract
+							-XepOpt:NullAway:SuppressionNameAliases=DataFlowIssue
+							<!-- https://github.com/uber/NullAway/issues/162 -->
+							-XepExcludedPaths:.*/src/test/java/.*
 						</compilerArg>
 					</compilerArgs>
 					<annotationProcessorPaths>
@@ -188,6 +197,11 @@
 							<artifactId>error_prone_core</artifactId>
 							<version>${error-prone.version}</version>
 						</path>
+						<path>
+							<groupId>com.uber.nullaway</groupId>
+							<artifactId>nullaway</artifactId>
+							<version>${nullaway.version}</version>
+						</path>
 					</annotationProcessorPaths>
 				</configuration>
 			</plugin>

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

@@ -16,6 +16,8 @@
 
 package org.springframework.batch.item;
 
+import org.jspecify.annotations.Nullable;
+
 import java.io.Serializable;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -34,6 +36,7 @@
  * @author Dave Syer
  * @author Mahmoud Ben Hassine
  * @author Jinwoo Bae
+ * @author Stefano Cordio
  * @since 2.0
  */
 public class Chunk<W> implements Iterable<W>, Serializable {
@@ -44,7 +47,7 @@ public class Chunk<W> implements Iterable<W>, Serializable {
 
 	private final List<Exception> errors = new ArrayList<>();
 
-	private Object userData;
+	private @Nullable Object userData;
 
 	private boolean end;
 
@@ -65,8 +68,7 @@ public Chunk(List<? extends W> items) {
 	}
 
 	@Deprecated(since = "6.0", forRemoval = true)
-	public Chunk(List<? extends W> items, List<SkipWrapper<W>> skips) {
-		super();
+	public Chunk(@Nullable List<? extends W> items, @Nullable List<SkipWrapper<W>> skips) {
 		if (items != null) {
 			this.items.addAll(items);
 		}
@@ -218,7 +220,7 @@ public void clearSkips() {
 	}
 
 	@Deprecated(since = "6.0", forRemoval = true)
-	public Object getUserData() {
+	public @Nullable Object getUserData() {
 		return userData;
 	}
 
@@ -266,9 +268,9 @@ public int hashCode() {
 	 */
 	public class ChunkIterator implements Iterator<W> {
 
-		final private Iterator<W> iterator;
+		private final Iterator<W> iterator;
 
-		private W next;
+		private @Nullable W next;
 
 		public ChunkIterator(List<W> items) {
 			iterator = items.iterator();

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

@@ -23,7 +23,7 @@
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Object representing a context for an {@link ItemStream}. It is a thin wrapper for a map
@@ -254,8 +254,7 @@ public double getDouble(String key, double defaultDouble) {
 	 * @return The value represented by the given key or {@code null} if the key is not
 	 * present
 	 */
-	@Nullable
-	public Object get(String key) {
+	public @Nullable Object get(String key) {
 		return this.map.get(key);
 	}
 
@@ -269,8 +268,7 @@ public Object get(String key) {
 	 * key is not present
 	 * @since 5.1
 	 */
-	@Nullable
-	public <V> V get(String key, Class<V> type) {
+	public <V> @Nullable V get(String key, Class<V> type) {
 		Object value = this.map.get(key);
 		if (value == null) {
 			return null;
@@ -289,8 +287,7 @@ public <V> V get(String key, Class<V> type) {
 	 * if the key is not present
 	 * @since 5.1
 	 */
-	@Nullable
-	public <V> V get(String key, Class<V> type, @Nullable V defaultValue) {
+	public <V> @Nullable V get(String key, Class<V> type, @Nullable V defaultValue) {
 		Object value = this.map.get(key);
 		if (value == null) {
 			return defaultValue;
@@ -373,8 +370,7 @@ public boolean containsKey(String key) {
 	 *
 	 * @see java.util.Map#remove(Object)
 	 */
-	@Nullable
-	public Object remove(String key) {
+	public @Nullable Object remove(String key) {
 		return this.map.remove(key);
 	}
 

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

@@ -16,8 +16,7 @@
 
 package org.springframework.batch.item;
 
-import org.springframework.lang.NonNull;
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Interface for item transformation. Given an item as input, this interface provides an
@@ -53,7 +52,6 @@ public interface ItemProcessor<I, O> {
 	 * processing of the provided item should not continue.
 	 * @throws Exception thrown if exception occurs during processing.
 	 */
-	@Nullable
-	O process(@NonNull I item) throws Exception;
+	@Nullable O process(I item) throws Exception;
 
 }

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

@@ -16,7 +16,7 @@
 
 package org.springframework.batch.item;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Strategy interface for providing the data. <br>
@@ -57,7 +57,6 @@ public interface ItemReader<T> {
 	 * @throws Exception if an there is a non-specific error.
 	 * @return T the item to be processed or {@code null} if the data source is exhausted
 	 */
-	@Nullable
-	T read() throws Exception, UnexpectedInputException, ParseException, NonTransientResourceException;
+	@Nullable T read() throws Exception, UnexpectedInputException, ParseException, NonTransientResourceException;
 
 }

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

@@ -15,12 +15,15 @@
  */
 package org.springframework.batch.item;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Exception representing any errors encountered while processing a stream.
  *
  * @author Dave Syer
  * @author Lucas Ward
  * @author Mahmoud Ben Hassine
+ * @author Stefano Cordio
  */
 public class ItemStreamException extends RuntimeException {
 
@@ -33,11 +36,10 @@ public ItemStreamException(String message) {
 
 	/**
 	 * Constructs a new instance with a message and nested exception.
-	 * @param msg the exception message.
+	 * @param msg the exception message (can be {@code null}).
 	 * @param nested the cause of the exception.
-	 *
 	 */
-	public ItemStreamException(String msg, Throwable nested) {
+	public ItemStreamException(@Nullable String msg, Throwable nested) {
 		super(msg, nested);
 	}
 

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

@@ -15,6 +15,7 @@
  */
 package org.springframework.batch.item;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.batch.item.util.ExecutionContextUserSupport;
 
 /**
@@ -23,6 +24,7 @@
  * @author Dave Syer
  * @author Dean de Bree
  * @author Mahmoud Ben Hassine
+ * @author Stefano Cordio
  *
  */
 public abstract class ItemStreamSupport implements ItemStream {
@@ -43,7 +45,7 @@ public void setName(String name) {
 	 * Get the name of the component
 	 * @return the name of the component
 	 */
-	public String getName() {
+	public @Nullable String getName() {
 		return executionContextUserSupport.getName();
 	}
 

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

@@ -16,8 +16,6 @@
 
 package org.springframework.batch.item;
 
-import org.springframework.lang.NonNull;
-
 /**
  * <p>
  * Basic interface for generic output operations. Class implementing this interface will
@@ -48,6 +46,6 @@ public interface ItemWriter<T> {
 	 * @throws Exception if there are errors. The framework will catch the exception and
 	 * convert or rethrow it as appropriate.
 	 */
-	void write(@NonNull Chunk<? extends T> chunk) throws Exception;
+	void write(Chunk<? extends T> chunk) throws Exception;
 
 }

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

@@ -12,6 +12,7 @@
  */
 package org.springframework.batch.item;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.core.convert.converter.Converter;
 import org.springframework.util.Assert;
@@ -22,21 +23,20 @@
  *
  * @author David Turanski
  * @author Mahmoud Ben Hassine
+ * @author Stefano Cordio
  * @since 2.2
  *
  */
 public abstract class KeyValueItemWriter<K, V> implements ItemWriter<V>, InitializingBean {
 
-	protected Converter<V, K> itemKeyMapper;
+	protected @Nullable Converter<V, K> itemKeyMapper;
 
 	protected boolean delete;
 
 	@Override
-	public void write(Chunk<? extends V> items) throws Exception {
-		if (items == null) {
-			return;
-		}
-		for (V item : items) {
+	public void write(Chunk<? extends V> chunk) throws Exception {
+		for (V item : chunk) {
+			@SuppressWarnings("DataFlowIssue")
 			K key = itemKeyMapper.convert(item);
 			writeKeyValue(key, item);
 		}
@@ -55,7 +55,7 @@ protected void flush() throws Exception {
 	 * @param key the key
 	 * @param value the item
 	 */
-	protected abstract void writeKeyValue(K key, V value);
+	protected abstract void writeKeyValue(@Nullable K key, V value);
 
 	/**
 	 * afterPropertiesSet() hook

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

@@ -15,7 +15,7 @@
  */
 package org.springframework.batch.item;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * <p>
@@ -45,7 +45,6 @@ public interface PeekableItemReader<T> extends ItemReader<T> {
 	 * @return the next item or {@code null} if the data source is exhausted
 	 * @throws Exception if there is a problem
 	 */
-	@Nullable
-	T peek() throws Exception, UnexpectedInputException, ParseException;
+	@Nullable T peek() throws Exception, UnexpectedInputException, ParseException;
 
 }

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

@@ -16,21 +16,22 @@
 
 package org.springframework.batch.item;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Wrapper for an item and its exception if it failed processing.
  *
  * @author Dave Syer
  * @author Mahmoud Ben Hassine
+ * @author Stefano Cordio
  * @deprecated since 6.0 with no replacement. Scheduled for removal in 7.0.
  */
 @Deprecated(since = "6.0", forRemoval = true)
 public class SkipWrapper<T> {
 
-	final private Throwable exception;
+	private final @Nullable Throwable exception;
 
-	final private T item;
+	private final @Nullable T item;
 
 	/**
 	 * @param item the item being wrapped.
@@ -39,7 +40,7 @@ public SkipWrapper(T item) {
 		this(item, null);
 	}
 
-	public SkipWrapper(T item, @Nullable Throwable e) {
+	public SkipWrapper(@Nullable T item, @Nullable Throwable e) {
 		this.item = item;
 		this.exception = e;
 	}
@@ -48,16 +49,15 @@ public SkipWrapper(T item, @Nullable Throwable e) {
 	 * Public getter for the exception.
 	 * @return the exception
 	 */
-	@Nullable
-	public Throwable getException() {
+	public @Nullable Throwable getException() {
 		return exception;
 	}
 
 	/**
 	 * Public getter for the item.
 	 * @return the item
 	 */
-	public T getItem() {
+	public @Nullable T getItem() {
 		return item;
 	}