GH-10083: Apply Nullability to some core support packages

spring-integration-core/src/main/java/org/springframework/integration/context/IntegrationObjectSupport.java

@@ -142,9 +142,8 @@ public void setComponentName(String componentName) {
 	 * Subclasses may implement this method to provide component type information.
 	 */
 	@Override
-	@Nullable
 	public String getComponentType() {
-		return null;
+		return "integration-object-support";
 	}
 
 	@Override

spring-integration-core/src/main/java/org/springframework/integration/support/channel/BeanFactoryChannelResolver.java

@@ -21,6 +21,7 @@
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.BeanFactory;
@@ -52,9 +53,10 @@ public class BeanFactoryChannelResolver implements DestinationResolver<MessageCh
 
 	private final Lock lock = new ReentrantLock();
 
+	@SuppressWarnings("NullAway.Init")
 	private BeanFactory beanFactory;
 
-	private HeaderChannelRegistry replyChannelRegistry;
+	private @Nullable HeaderChannelRegistry replyChannelRegistry;
 
 	private volatile boolean initialized;
 
@@ -89,7 +91,6 @@ public void setBeanFactory(BeanFactory beanFactory) {
 
 	@Override
 	public MessageChannel resolveDestination(String name) {
-		Assert.state(this.beanFactory != null, "BeanFactory is required");
 		try {
 			return this.beanFactory.getBean(name, MessageChannel.class);
 		}

spring-integration-core/src/main/java/org/springframework/integration/support/channel/HeaderChannelRegistry.java

@@ -16,6 +16,8 @@
 
 package org.springframework.integration.support.channel;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.jmx.export.annotation.ManagedAttribute;
 import org.springframework.jmx.export.annotation.ManagedOperation;
 import org.springframework.messaging.MessageChannel;
@@ -37,7 +39,7 @@ public interface HeaderChannelRegistry {
 	 * @param channel The channel.
 	 * @return The channel name, or the channel if it is not a MessageChannel.
 	 */
-	Object channelToChannelName(Object channel);
+	@Nullable Object channelToChannelName(Object channel);
 
 	/**
 	 * Converts the channel to a name (String). If the channel is not a
@@ -48,15 +50,15 @@ public interface HeaderChannelRegistry {
 	 * @return The channel name, or the channel if it is not a MessageChannel.
 	 * @since 4.1
 	 */
-	Object channelToChannelName(Object channel, long timeToLive);
+	@Nullable Object channelToChannelName(Object channel, long timeToLive);
 
 	/**
 	 * Converts the channel name back to a {@link MessageChannel} (if it is
 	 * registered).
 	 * @param name The name of the channel.
 	 * @return The channel, or null if there is no channel registered with the name.
 	 */
-	MessageChannel channelNameToChannel(String name);
+	@Nullable MessageChannel channelNameToChannel(String name);
 
 	/**
 	 * @return the current size of the registry

spring-integration-core/src/main/java/org/springframework/integration/support/channel/package-info.java

@@ -0,0 +1,5 @@
+/**
+ * Provides classes supporting use of the channel.
+ */
+@org.jspecify.annotations.NullMarked
+package org.springframework.integration.support.channel;

spring-integration-core/src/main/java/org/springframework/integration/support/context/package-info.java

@@ -1,4 +1,5 @@
 /**
  * Provides classes supporting use of the application context.
  */
+@org.jspecify.annotations.NullMarked
 package org.springframework.integration.support.context;

spring-integration-core/src/main/java/org/springframework/integration/support/converter/AllowListDeserializingConverter.java

@@ -57,8 +57,7 @@ public class AllowListDeserializingConverter implements Converter<byte[], Object
 
 	private final Deserializer<Object> deserializer;
 
-	@Nullable
-	private final ClassLoader defaultDeserializerClassLoader;
+	private final @Nullable ClassLoader defaultDeserializerClassLoader;
 
 	private final boolean usingDefaultDeserializer;
 
@@ -136,15 +135,14 @@ public Object convert(byte[] source) {
 			if (this.usingDefaultDeserializer) {
 				return deserialize(byteStream);
 			}
-			else {
-				Object result = this.deserializer.deserialize(byteStream);
-				/* Even if there is no knowledge what is the target deserialization algorithm
-				 and malicious code may be executed already, it is still better to fail
-				 with untrusted data rather than just let it pass downstream.
-				 */
-				checkAllowList(result.getClass());
-				return result;
-			}
+
+			Object result = this.deserializer.deserialize(byteStream);
+			/* Even if there is no knowledge what is the target deserialization algorithm
+			 and malicious code may be executed already, it is still better to fail
+			 with untrusted data rather than just let it pass downstream.
+			 */
+			checkAllowList(result.getClass());
+			return result;
 		}
 		catch (Exception ex) {
 			throw new SerializationFailedException("Failed to deserialize payload. " +

spring-integration-core/src/main/java/org/springframework/integration/support/converter/DefaultDatatypeChannelMessageConverter.java

@@ -72,13 +72,11 @@ public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
 	 * @return the converted payload or null if conversion is not possible.
 	 */
 	@Override
-	public Object fromMessage(Message<?> message, Class<?> targetClass) {
+	public @Nullable Object fromMessage(Message<?> message, Class<?> targetClass) {
 		if (this.conversionService.canConvert(message.getPayload().getClass(), targetClass)) {
 			return this.conversionService.convert(message.getPayload(), targetClass);
 		}
-		else {
-			return null;
-		}
+		return null;
 	}
 
 	@Override

spring-integration-core/src/main/java/org/springframework/integration/support/converter/MapMessageConverter.java

@@ -49,7 +49,7 @@ public class MapMessageConverter implements MessageConverter, BeanFactoryAware {
 
 	private boolean filterHeadersInToMessage;
 
-	private BeanFactory beanFactory;
+	private @Nullable BeanFactory beanFactory;
 
 	private MessageBuilderFactory messageBuilderFactory = new DefaultMessageBuilderFactory();
 
@@ -97,7 +97,6 @@ public void setFilterHeadersInToMessage(boolean filterHeadersInToMessage) {
 		this.filterHeadersInToMessage = filterHeadersInToMessage;
 	}
 
-	@Nullable
 	@Override
 	public Message<?> toMessage(Object object, @Nullable MessageHeaders messageHeaders) {
 		Assert.isInstanceOf(Map.class, object, "This converter expects a Map");
@@ -119,7 +118,6 @@ public Message<?> toMessage(Object object, @Nullable MessageHeaders messageHeade
 				.build();
 	}
 
-	@Nullable
 	@Override
 	public Object fromMessage(Message<?> message, Class<?> clazz) {
 		Map<String, Object> map = new HashMap<>();

spring-integration-core/src/main/java/org/springframework/integration/support/converter/ObjectStringMessageConverter.java

@@ -56,9 +56,7 @@ protected Object convertFromInternal(Message<?> message, Class<?> targetClass, @
 		if (payload instanceof String || payload instanceof byte[]) {
 			return super.convertFromInternal(message, targetClass, conversionHint);
 		}
-		else {
-			return payload.toString();
-		}
+		return payload.toString();
 	}
 
 }

spring-integration-core/src/main/java/org/springframework/integration/support/converter/PassThruMessageConverter.java

@@ -43,13 +43,12 @@ public Object fromMessage(Message<?> message, Class<?> targetClass) {
 	}
 
 	@Override
-	public Message<?> toMessage(Object payload, @Nullable MessageHeaders headers) {
+	public @Nullable Message<?> toMessage(Object payload, @Nullable MessageHeaders headers) {
 		if (payload instanceof byte[]) {
 			return MessageBuilder.withPayload(payload).copyHeaders(headers).build();
 		}
-		else {
-			return null;
-		}
+
+		return null;
 	}
 
 }

spring-integration-core/src/main/java/org/springframework/integration/support/converter/SimpleMessageConverter.java

@@ -51,7 +51,7 @@ public class SimpleMessageConverter implements MessageConverter, BeanFactoryAwar
 
 	private boolean messageBuilderFactorySet;
 
-	private BeanFactory beanFactory;
+	private @Nullable BeanFactory beanFactory;
 
 	public SimpleMessageConverter() {
 	}
@@ -104,9 +104,8 @@ protected MessageBuilderFactory getMessageBuilderFactory() {
 		return this.messageBuilderFactory;
 	}
 
-	@Nullable
 	@Override
-	public Message<?> toMessage(Object object, @Nullable MessageHeaders headers) {
+	public @Nullable Message<?> toMessage(Object object, @Nullable MessageHeaders headers) {
 		try {
 			return this.inboundMessageMapper.toMessage(object, headers);
 		}
@@ -115,9 +114,8 @@ public Message<?> toMessage(Object object, @Nullable MessageHeaders headers) {
 		}
 	}
 
-	@Nullable
 	@Override
-	public Object fromMessage(Message<?> message, Class<?> targetClass) {
+	public @Nullable Object fromMessage(Message<?> message, Class<?> targetClass) {
 		try {
 			return this.outboundMessageMapper.fromMessage(message);
 		}
@@ -132,7 +130,7 @@ private class DefaultInboundMessageMapper implements InboundMessageMapper<Object
 		}
 
 		@Override
-		public Message<?> toMessage(@Nullable Object object, @Nullable Map<String, Object> headers) {
+		public @Nullable Message<?> toMessage(@Nullable Object object, @Nullable Map<String, Object> headers) {
 			if (object == null) {
 				return null;
 			}
@@ -153,8 +151,8 @@ private static class DefaultOutboundMessageMapper implements OutboundMessageMapp
 		}
 
 		@Override
-		public Object fromMessage(@Nullable Message<?> message) {
-			return (message != null) ? message.getPayload() : null;
+		public Object fromMessage(Message<?> message) {
+			return message.getPayload();
 		}
 
 	}

spring-integration-core/src/main/java/org/springframework/integration/support/converter/package-info.java

@@ -1,6 +1,5 @@
 /**
  * Provides classes supporting message conversion.
  */
-@org.springframework.lang.NonNullApi
-@org.springframework.lang.NonNullFields
+@org.jspecify.annotations.NullMarked
 package org.springframework.integration.support.converter;