Switch to JSpecify annotations

This commit updates the whole Spring Framework codebase to use JSpecify
annotations instead of Spring null-safety annotations with JSR 305
semantics.

JSpecify provides signficant enhancements such as properly defined
specifications, a canonical dependency with no split-package issue,
better tooling, better Kotlin integration and the capability to specify
generic type, array and varargs element null-safety. Generic type
null-safety is not defined by this commit yet and will be specified
later.

A key difference is that Spring null-safety annotations, following
JSR 305 semantics, apply to fields, parameters and return values,
while JSpecify annotations apply to type usages. That's why this
commit moves nullability annotations closer to the type for fields
and return values.

See gh-28797

spring-messaging/src/main/java/org/springframework/messaging/MessageDeliveryException.java

@@ -16,7 +16,7 @@
 
 package org.springframework.messaging;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Exception that indicates an error occurred during message delivery.

spring-messaging/src/main/java/org/springframework/messaging/MessageHeaders.java

@@ -30,8 +30,8 @@ import java.util.UUID;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
-import org.springframework.lang.Nullable;
 import org.springframework.util.AlternativeJdkIdGenerator;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.IdGenerator;
@@ -112,8 +112,7 @@ public class MessageHeaders implements Map<String, Object>, Serializable {
 
 	private static final IdGenerator defaultIdGenerator = new AlternativeJdkIdGenerator();
 
-	@Nullable
-	private static volatile IdGenerator idGenerator;
+	private static volatile @Nullable IdGenerator idGenerator;
 
 	@SuppressWarnings("serial")
 	private final Map<String, Object> headers;
@@ -183,30 +182,25 @@ public class MessageHeaders implements Map<String, Object>, Serializable {
 		return (generator != null ? generator : defaultIdGenerator);
 	}
 
-	@Nullable
-	public UUID getId() {
+	public @Nullable UUID getId() {
 		return get(ID, UUID.class);
 	}
 
-	@Nullable
-	public Long getTimestamp() {
+	public @Nullable Long getTimestamp() {
 		return get(TIMESTAMP, Long.class);
 	}
 
-	@Nullable
-	public Object getReplyChannel() {
+	public @Nullable Object getReplyChannel() {
 		return get(REPLY_CHANNEL);
 	}
 
-	@Nullable
-	public Object getErrorChannel() {
+	public @Nullable Object getErrorChannel() {
 		return get(ERROR_CHANNEL);
 	}
 
 
 	@SuppressWarnings("unchecked")
-	@Nullable
-	public <T> T get(Object key, Class<T> type) {
+	public <T> @Nullable T get(Object key, Class<T> type) {
 		Object value = this.headers.get(key);
 		if (value == null) {
 			return null;
@@ -237,8 +231,7 @@ public class MessageHeaders implements Map<String, Object>, Serializable {
 	}
 
 	@Override
-	@Nullable
-	public Object get(Object key) {
+	public @Nullable Object get(Object key) {
 		return this.headers.get(key);
 	}
 

spring-messaging/src/main/java/org/springframework/messaging/MessagingException.java

@@ -16,8 +16,9 @@
 
 package org.springframework.messaging;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.NestedRuntimeException;
-import org.springframework.lang.Nullable;
 
 /**
  * The base exception for any failures related to messaging.
@@ -29,8 +30,7 @@ import org.springframework.lang.Nullable;
 @SuppressWarnings("serial")
 public class MessagingException extends NestedRuntimeException {
 
-	@Nullable
-	private final Message<?> failedMessage;
+	private final @Nullable Message<?> failedMessage;
 
 
 	public MessagingException(Message<?> message) {
@@ -64,8 +64,7 @@ public class MessagingException extends NestedRuntimeException {
 	}
 
 
-	@Nullable
-	public Message<?> getFailedMessage() {
+	public @Nullable Message<?> getFailedMessage() {
 		return this.failedMessage;
 	}
 

spring-messaging/src/main/java/org/springframework/messaging/PollableChannel.java

@@ -16,7 +16,7 @@
 
 package org.springframework.messaging;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * A {@link MessageChannel} from which messages may be actively received through polling.
@@ -30,8 +30,7 @@ public interface PollableChannel extends MessageChannel {
 	 * Receive a message from this channel, blocking indefinitely if necessary.
 	 * @return the next available {@link Message} or {@code null} if interrupted
 	 */
-	@Nullable
-	Message<?> receive();
+	@Nullable Message<?> receive();
 
 	/**
 	 * Receive a message from this channel, blocking until either a message is available
@@ -40,7 +39,6 @@ public interface PollableChannel extends MessageChannel {
 	 * @return the next available {@link Message} or {@code null} if the specified timeout
 	 * period elapses or the message receipt is interrupted
 	 */
-	@Nullable
-	Message<?> receive(long timeout);
+	@Nullable Message<?> receive(long timeout);
 
 }

spring-messaging/src/main/java/org/springframework/messaging/converter/AbstractJsonMessageConverter.java

@@ -28,7 +28,8 @@ import java.lang.reflect.Type;
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHeaders;
 import org.springframework.util.ClassUtils;
@@ -62,8 +63,7 @@ public abstract class AbstractJsonMessageConverter extends AbstractMessageConver
 	}
 
 	@Override
-	@Nullable
-	protected Object convertFromInternal(Message<?> message, Class<?> targetClass, @Nullable Object conversionHint) {
+	protected @Nullable Object convertFromInternal(Message<?> message, Class<?> targetClass, @Nullable Object conversionHint) {
 		try {
 			Type resolvedType = getResolvedType(targetClass, conversionHint);
 			Object payload = message.getPayload();
@@ -84,8 +84,7 @@ public abstract class AbstractJsonMessageConverter extends AbstractMessageConver
 	}
 
 	@Override
-	@Nullable
-	protected Object convertToInternal(Object payload, @Nullable MessageHeaders headers, @Nullable Object conversionHint) {
+	protected @Nullable Object convertToInternal(Object payload, @Nullable MessageHeaders headers, @Nullable Object conversionHint) {
 		try {
 			Type resolvedType = getResolvedType(payload.getClass(), conversionHint);
 			if (byte[].class == getSerializedPayloadClass()) {

spring-messaging/src/main/java/org/springframework/messaging/converter/AbstractMessageConverter.java

@@ -25,10 +25,10 @@ import java.util.List;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.core.GenericTypeResolver;
 import org.springframework.core.MethodParameter;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHeaders;
 import org.springframework.messaging.support.MessageBuilder;
@@ -53,8 +53,7 @@ public abstract class AbstractMessageConverter implements SmartMessageConverter
 
 	private final List<MimeType> supportedMimeTypes = new ArrayList<>(4);
 
-	@Nullable
-	private ContentTypeResolver contentTypeResolver = new DefaultContentTypeResolver();
+	private @Nullable ContentTypeResolver contentTypeResolver = new DefaultContentTypeResolver();
 
 	private boolean strictContentTypeMatch = false;
 
@@ -116,8 +115,7 @@ public abstract class AbstractMessageConverter implements SmartMessageConverter
 	 * Return the {@link #setContentTypeResolver(ContentTypeResolver) configured}
 	 * {@code ContentTypeResolver}.
 	 */
-	@Nullable
-	public ContentTypeResolver getContentTypeResolver() {
+	public @Nullable ContentTypeResolver getContentTypeResolver() {
 		return this.contentTypeResolver;
 	}
 
@@ -169,14 +167,12 @@ public abstract class AbstractMessageConverter implements SmartMessageConverter
 
 
 	@Override
-	@Nullable
-	public final Object fromMessage(Message<?> message, Class<?> targetClass) {
+	public final @Nullable Object fromMessage(Message<?> message, Class<?> targetClass) {
 		return fromMessage(message, targetClass, null);
 	}
 
 	@Override
-	@Nullable
-	public final Object fromMessage(Message<?> message, Class<?> targetClass, @Nullable Object conversionHint) {
+	public final @Nullable Object fromMessage(Message<?> message, Class<?> targetClass, @Nullable Object conversionHint) {
 		if (!canConvertFrom(message, targetClass)) {
 			return null;
 		}
@@ -184,14 +180,12 @@ public abstract class AbstractMessageConverter implements SmartMessageConverter
 	}
 
 	@Override
-	@Nullable
-	public final Message<?> toMessage(Object payload, @Nullable MessageHeaders headers) {
+	public final @Nullable Message<?> toMessage(Object payload, @Nullable MessageHeaders headers) {
 		return toMessage(payload, headers, null);
 	}
 
 	@Override
-	@Nullable
-	public final Message<?> toMessage(
+	public final @Nullable Message<?> toMessage(
 			Object payload, @Nullable MessageHeaders headers, @Nullable Object conversionHint) {
 
 		if (!canConvertTo(payload, headers)) {
@@ -249,8 +243,7 @@ public abstract class AbstractMessageConverter implements SmartMessageConverter
 		return false;
 	}
 
-	@Nullable
-	protected MimeType getMimeType(@Nullable MessageHeaders headers) {
+	protected @Nullable MimeType getMimeType(@Nullable MessageHeaders headers) {
 		return (this.contentTypeResolver != null ? this.contentTypeResolver.resolve(headers) : null);
 	}
 
@@ -264,8 +257,7 @@ public abstract class AbstractMessageConverter implements SmartMessageConverter
 	 * @param payload the payload being converted to a message
 	 * @return the content type, or {@code null} if not known
 	 */
-	@Nullable
-	protected MimeType getDefaultContentType(Object payload) {
+	protected @Nullable MimeType getDefaultContentType(Object payload) {
 		List<MimeType> mimeTypes = getSupportedMimeTypes();
 		return (!mimeTypes.isEmpty() ? mimeTypes.get(0) : null);
 	}
@@ -288,8 +280,7 @@ public abstract class AbstractMessageConverter implements SmartMessageConverter
 	 * perform the conversion
 	 * @since 4.2
 	 */
-	@Nullable
-	protected Object convertFromInternal(
+	protected @Nullable Object convertFromInternal(
 			Message<?> message, Class<?> targetClass, @Nullable Object conversionHint) {
 
 		return null;
@@ -305,8 +296,7 @@ public abstract class AbstractMessageConverter implements SmartMessageConverter
 	 * cannot perform the conversion
 	 * @since 4.2
 	 */
-	@Nullable
-	protected Object convertToInternal(
+	protected @Nullable Object convertToInternal(
 			Object payload, @Nullable MessageHeaders headers, @Nullable Object conversionHint) {
 
 		return null;

spring-messaging/src/main/java/org/springframework/messaging/converter/ByteArrayMessageConverter.java

@@ -16,7 +16,8 @@
 
 package org.springframework.messaging.converter;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHeaders;
 import org.springframework.util.MimeTypeUtils;
@@ -41,16 +42,14 @@ public class ByteArrayMessageConverter extends AbstractMessageConverter {
 	}
 
 	@Override
-	@Nullable
-	protected Object convertFromInternal(
+	protected @Nullable Object convertFromInternal(
 			Message<?> message, @Nullable Class<?> targetClass, @Nullable Object conversionHint) {
 
 		return message.getPayload();
 	}
 
 	@Override
-	@Nullable
-	protected Object convertToInternal(
+	protected @Nullable Object convertToInternal(
 			Object payload, @Nullable MessageHeaders headers, @Nullable Object conversionHint) {
 
 		return payload;

spring-messaging/src/main/java/org/springframework/messaging/converter/CompositeMessageConverter.java

@@ -20,7 +20,8 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHeaders;
 import org.springframework.util.Assert;
@@ -51,8 +52,7 @@ public class CompositeMessageConverter implements SmartMessageConverter {
 
 
 	@Override
-	@Nullable
-	public Object fromMessage(Message<?> message, Class<?> targetClass) {
+	public @Nullable Object fromMessage(Message<?> message, Class<?> targetClass) {
 		for (MessageConverter converter : getConverters()) {
 			Object result = converter.fromMessage(message, targetClass);
 			if (result != null) {
@@ -63,8 +63,7 @@ public class CompositeMessageConverter implements SmartMessageConverter {
 	}
 
 	@Override
-	@Nullable
-	public Object fromMessage(Message<?> message, Class<?> targetClass, @Nullable Object conversionHint) {
+	public @Nullable Object fromMessage(Message<?> message, Class<?> targetClass, @Nullable Object conversionHint) {
 		for (MessageConverter converter : getConverters()) {
 			Object result = (converter instanceof SmartMessageConverter smartMessageConverter ?
 					smartMessageConverter.fromMessage(message, targetClass, conversionHint) :
@@ -77,8 +76,7 @@ public class CompositeMessageConverter implements SmartMessageConverter {
 	}
 
 	@Override
-	@Nullable
-	public Message<?> toMessage(Object payload, @Nullable MessageHeaders headers) {
+	public @Nullable Message<?> toMessage(Object payload, @Nullable MessageHeaders headers) {
 		for (MessageConverter converter : getConverters()) {
 			Message<?> result = converter.toMessage(payload, headers);
 			if (result != null) {
@@ -89,8 +87,7 @@ public class CompositeMessageConverter implements SmartMessageConverter {
 	}
 
 	@Override
-	@Nullable
-	public Message<?> toMessage(Object payload, @Nullable MessageHeaders headers, @Nullable Object conversionHint) {
+	public @Nullable Message<?> toMessage(Object payload, @Nullable MessageHeaders headers, @Nullable Object conversionHint) {
 		for (MessageConverter converter : getConverters()) {
 			Message<?> result = (converter instanceof SmartMessageConverter smartMessageConverter ?
 					smartMessageConverter.toMessage(payload, headers, conversionHint) :

spring-messaging/src/main/java/org/springframework/messaging/converter/ContentTypeResolver.java

@@ -16,7 +16,8 @@
 
 package org.springframework.messaging.converter;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.MessageHeaders;
 import org.springframework.util.InvalidMimeTypeException;
 import org.springframework.util.MimeType;
@@ -37,7 +38,6 @@ public interface ContentTypeResolver {
 	 * @throws InvalidMimeTypeException if the content type is a String that cannot be parsed
 	 * @throws IllegalArgumentException if there is a content type but its type is unknown
 	 */
-	@Nullable
-	MimeType resolve(@Nullable MessageHeaders headers) throws InvalidMimeTypeException;
+	@Nullable MimeType resolve(@Nullable MessageHeaders headers) throws InvalidMimeTypeException;
 
 }

spring-messaging/src/main/java/org/springframework/messaging/converter/DefaultContentTypeResolver.java

@@ -16,7 +16,8 @@
 
 package org.springframework.messaging.converter;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.MessageHeaders;
 import org.springframework.util.MimeType;
 
@@ -32,8 +33,7 @@ import org.springframework.util.MimeType;
  */
 public class DefaultContentTypeResolver implements ContentTypeResolver {
 
-	@Nullable
-	private MimeType defaultMimeType;
+	private @Nullable MimeType defaultMimeType;
 
 
 	/**
@@ -49,15 +49,13 @@ public class DefaultContentTypeResolver implements ContentTypeResolver {
 	 * Return the default MIME type to use if no
 	 * {@link MessageHeaders#CONTENT_TYPE} header is present.
 	 */
-	@Nullable
-	public MimeType getDefaultMimeType() {
+	public @Nullable MimeType getDefaultMimeType() {
 		return this.defaultMimeType;
 	}
 
 
 	@Override
-	@Nullable
-	public MimeType resolve(@Nullable MessageHeaders headers) {
+	public @Nullable MimeType resolve(@Nullable MessageHeaders headers) {
 		if (headers == null || headers.get(MessageHeaders.CONTENT_TYPE) == null) {
 			return this.defaultMimeType;
 		}

spring-messaging/src/main/java/org/springframework/messaging/converter/GenericMessageConverter.java

@@ -16,10 +16,11 @@
 
 package org.springframework.messaging.converter;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.convert.ConversionException;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.support.DefaultConversionService;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
@@ -58,8 +59,7 @@ public class GenericMessageConverter extends SimpleMessageConverter {
 
 
 	@Override
-	@Nullable
-	public Object fromMessage(Message<?> message, Class<?> targetClass) {
+	public @Nullable Object fromMessage(Message<?> message, Class<?> targetClass) {
 		Object payload = message.getPayload();
 		if (this.conversionService.canConvert(payload.getClass(), targetClass)) {
 			try {

spring-messaging/src/main/java/org/springframework/messaging/converter/MappingJackson2MessageConverter.java

@@ -34,9 +34,9 @@ import com.fasterxml.jackson.databind.JsonMappingException;
 import com.fasterxml.jackson.databind.MapperFeature;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.SerializationFeature;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.core.MethodParameter;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHeaders;
 import org.springframework.util.Assert;
@@ -64,8 +64,7 @@ public class MappingJackson2MessageConverter extends AbstractMessageConverter {
 
 	private ObjectMapper objectMapper;
 
-	@Nullable
-	private Boolean prettyPrint;
+	private @Nullable Boolean prettyPrint;
 
 
 	/**
@@ -227,8 +226,7 @@ public class MappingJackson2MessageConverter extends AbstractMessageConverter {
 	}
 
 	@Override
-	@Nullable
-	protected Object convertFromInternal(Message<?> message, Class<?> targetClass, @Nullable Object conversionHint) {
+	protected @Nullable Object convertFromInternal(Message<?> message, Class<?> targetClass, @Nullable Object conversionHint) {
 		JavaType javaType = this.objectMapper.constructType(getResolvedType(targetClass, conversionHint));
 		Object payload = message.getPayload();
 		Class<?> view = getSerializationView(conversionHint);
@@ -260,8 +258,7 @@ public class MappingJackson2MessageConverter extends AbstractMessageConverter {
 	}
 
 	@Override
-	@Nullable
-	protected Object convertToInternal(Object payload, @Nullable MessageHeaders headers,
+	protected @Nullable Object convertToInternal(Object payload, @Nullable MessageHeaders headers,
 			@Nullable Object conversionHint) {
 
 		try {
@@ -304,8 +301,7 @@ public class MappingJackson2MessageConverter extends AbstractMessageConverter {
 	 * @return the serialization view class, or {@code null} if none
 	 * @since 4.2
 	 */
-	@Nullable
-	protected Class<?> getSerializationView(@Nullable Object conversionHint) {
+	protected @Nullable Class<?> getSerializationView(@Nullable Object conversionHint) {
 		if (conversionHint instanceof MethodParameter param) {
 			JsonView annotation = (param.getParameterIndex() >= 0 ?
 					param.getParameterAnnotation(JsonView.class) : param.getMethodAnnotation(JsonView.class));

spring-messaging/src/main/java/org/springframework/messaging/converter/MarshallingMessageConverter.java

@@ -27,8 +27,9 @@ import javax.xml.transform.Source;
 import javax.xml.transform.stream.StreamResult;
 import javax.xml.transform.stream.StreamSource;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.beans.TypeMismatchException;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHeaders;
 import org.springframework.oxm.Marshaller;
@@ -51,11 +52,9 @@ import org.springframework.util.MimeType;
  */
 public class MarshallingMessageConverter extends AbstractMessageConverter {
 
-	@Nullable
-	private Marshaller marshaller;
+	private @Nullable Marshaller marshaller;
 
-	@Nullable
-	private Unmarshaller unmarshaller;
+	private @Nullable Unmarshaller unmarshaller;
 
 
 	/**
@@ -102,8 +101,7 @@ public class MarshallingMessageConverter extends AbstractMessageConverter {
 	/**
 	 * Return the configured Marshaller.
 	 */
-	@Nullable
-	public Marshaller getMarshaller() {
+	public @Nullable Marshaller getMarshaller() {
 		return this.marshaller;
 	}
 
@@ -117,8 +115,7 @@ public class MarshallingMessageConverter extends AbstractMessageConverter {
 	/**
 	 * Return the configured unmarshaller.
 	 */
-	@Nullable
-	public Unmarshaller getUnmarshaller() {
+	public @Nullable Unmarshaller getUnmarshaller() {
 		return this.unmarshaller;
 	}
 
@@ -142,8 +139,7 @@ public class MarshallingMessageConverter extends AbstractMessageConverter {
 	}
 
 	@Override
-	@Nullable
-	protected Object convertFromInternal(Message<?> message, Class<?> targetClass, @Nullable Object conversionHint) {
+	protected @Nullable Object convertFromInternal(Message<?> message, Class<?> targetClass, @Nullable Object conversionHint) {
 		Assert.state(this.unmarshaller != null, "Property 'unmarshaller' is required");
 		try {
 			Source source = getSource(message.getPayload());
@@ -168,8 +164,7 @@ public class MarshallingMessageConverter extends AbstractMessageConverter {
 	}
 
 	@Override
-	@Nullable
-	protected Object convertToInternal(Object payload, @Nullable MessageHeaders headers,
+	protected @Nullable Object convertToInternal(Object payload, @Nullable MessageHeaders headers,
 			@Nullable Object conversionHint) {
 
 		Assert.state(this.marshaller != null, "Property 'marshaller' is required");

spring-messaging/src/main/java/org/springframework/messaging/converter/MessageConversionException.java

@@ -16,7 +16,8 @@
 
 package org.springframework.messaging.converter;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessagingException;
 

spring-messaging/src/main/java/org/springframework/messaging/converter/MessageConverter.java

@@ -16,7 +16,8 @@
 
 package org.springframework.messaging.converter;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHeaders;
 
@@ -42,8 +43,7 @@ public interface MessageConverter {
 	 * @return the result of the conversion, or {@code null} if the converter cannot
 	 * perform the conversion
 	 */
-	@Nullable
-	Object fromMessage(Message<?> message, Class<?> targetClass);
+	@Nullable Object fromMessage(Message<?> message, Class<?> targetClass);
 
 	/**
 	 * Create a {@link Message} whose payload is the result of converting the given
@@ -58,7 +58,6 @@ public interface MessageConverter {
 	 * @return the new message, or {@code null} if the converter does not support the
 	 * Object type or the target media type
 	 */
-	@Nullable
-	Message<?> toMessage(Object payload, @Nullable MessageHeaders headers);
+	@Nullable Message<?> toMessage(Object payload, @Nullable MessageHeaders headers);
 
 }

spring-messaging/src/main/java/org/springframework/messaging/converter/ProtobufJsonFormatMessageConverter.java

@@ -18,8 +18,7 @@ package org.springframework.messaging.converter;
 
 import com.google.protobuf.ExtensionRegistry;
 import com.google.protobuf.util.JsonFormat;
-
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Subclass of {@link ProtobufMessageConverter} for use with the official
@@ -52,7 +51,7 @@ public class ProtobufJsonFormatMessageConverter extends ProtobufMessageConverter
 	 * JsonFormat.Printer}, and a default instance of {@link ExtensionRegistry}.
 	 */
 	public ProtobufJsonFormatMessageConverter(
-			@Nullable JsonFormat.Parser parser, @Nullable JsonFormat.Printer printer) {
+			JsonFormat.@Nullable Parser parser, JsonFormat.@Nullable Printer printer) {
 
 		this(parser, printer, null);
 	}
@@ -62,8 +61,8 @@ public class ProtobufJsonFormatMessageConverter extends ProtobufMessageConverter
 	 * JsonFormat.Parser}, {@link com.google.protobuf.util.JsonFormat.Printer
 	 * JsonFormat.Printer}, and {@link ExtensionRegistry}.
 	 */
-	public ProtobufJsonFormatMessageConverter(@Nullable JsonFormat.Parser parser,
-			@Nullable JsonFormat.Printer printer, @Nullable ExtensionRegistry extensionRegistry) {
+	public ProtobufJsonFormatMessageConverter(JsonFormat.@Nullable Parser parser,
+			JsonFormat.@Nullable Printer printer, @Nullable ExtensionRegistry extensionRegistry) {
 
 		super(new ProtobufJavaUtilSupport(parser, printer), extensionRegistry);
 	}

spring-messaging/src/main/java/org/springframework/messaging/converter/ProtobufMessageConverter.java

@@ -28,8 +28,8 @@ import java.util.Map;
 import com.google.protobuf.ExtensionRegistry;
 import com.google.protobuf.Message;
 import com.google.protobuf.util.JsonFormat;
+import org.jspecify.annotations.Nullable;
 
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.MessageHeaders;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ConcurrentReferenceHashMap;
@@ -75,8 +75,7 @@ public class ProtobufMessageConverter extends AbstractMessageConverter {
 
 	final ExtensionRegistry extensionRegistry;
 
-	@Nullable
-	private final ProtobufFormatSupport protobufFormatSupport;
+	private final @Nullable ProtobufFormatSupport protobufFormatSupport;
 
 
 	/**
@@ -244,7 +243,7 @@ public class ProtobufMessageConverter extends AbstractMessageConverter {
 
 		private final JsonFormat.Printer printer;
 
-		public ProtobufJavaUtilSupport(@Nullable JsonFormat.Parser parser, @Nullable JsonFormat.Printer printer) {
+		public ProtobufJavaUtilSupport(JsonFormat.@Nullable Parser parser, JsonFormat.@Nullable Printer printer) {
 			this.parser = (parser != null ? parser : JsonFormat.parser());
 			this.printer = (printer != null ? printer : JsonFormat.printer());
 		}

spring-messaging/src/main/java/org/springframework/messaging/converter/SimpleMessageConverter.java

@@ -16,7 +16,8 @@
 
 package org.springframework.messaging.converter;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHeaders;
 import org.springframework.messaging.support.MessageBuilder;
@@ -36,8 +37,7 @@ import org.springframework.util.ClassUtils;
 public class SimpleMessageConverter implements MessageConverter {
 
 	@Override
-	@Nullable
-	public Object fromMessage(Message<?> message, Class<?> targetClass) {
+	public @Nullable Object fromMessage(Message<?> message, Class<?> targetClass) {
 		Object payload = message.getPayload();
 		return (ClassUtils.isAssignableValue(targetClass, payload) ? payload : null);
 	}

spring-messaging/src/main/java/org/springframework/messaging/converter/SmartMessageConverter.java

@@ -16,7 +16,8 @@
 
 package org.springframework.messaging.converter;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHeaders;
 
@@ -44,8 +45,7 @@ public interface SmartMessageConverter extends MessageConverter {
 	 * perform the conversion
 	 * @see #fromMessage(Message, Class)
 	 */
-	@Nullable
-	Object fromMessage(Message<?> message, Class<?> targetClass, @Nullable Object conversionHint);
+	@Nullable Object fromMessage(Message<?> message, Class<?> targetClass, @Nullable Object conversionHint);
 
 	/**
 	 * A variant of {@link #toMessage(Object, MessageHeaders)} which takes an extra
@@ -59,7 +59,6 @@ public interface SmartMessageConverter extends MessageConverter {
 	 * Object type or the target media type
 	 * @see #toMessage(Object, MessageHeaders)
 	 */
-	@Nullable
-	Message<?> toMessage(Object payload, @Nullable MessageHeaders headers, @Nullable Object conversionHint);
+	@Nullable Message<?> toMessage(Object payload, @Nullable MessageHeaders headers, @Nullable Object conversionHint);
 
 }

spring-messaging/src/main/java/org/springframework/messaging/converter/StringMessageConverter.java

@@ -19,7 +19,8 @@ package org.springframework.messaging.converter;
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHeaders;
 import org.springframework.util.Assert;
@@ -61,8 +62,7 @@ public class StringMessageConverter extends AbstractMessageConverter {
 	}
 
 	@Override
-	@Nullable
-	protected Object convertToInternal(
+	protected @Nullable Object convertToInternal(
 			Object payload, @Nullable MessageHeaders headers, @Nullable Object conversionHint) {
 
 		if (byte[].class == getSerializedPayloadClass()) {

spring-messaging/src/main/java/org/springframework/messaging/converter/package-info.java

@@ -1,9 +1,7 @@
 /**
  * Provides support for message conversion.
  */
-@NonNullApi
-@NonNullFields
+@NullMarked
 package org.springframework.messaging.converter;
 
-import org.springframework.lang.NonNullApi;
-import org.springframework.lang.NonNullFields;
+import org.jspecify.annotations.NullMarked;

spring-messaging/src/main/java/org/springframework/messaging/core/AbstractDestinationResolvingMessagingTemplate.java

@@ -18,7 +18,8 @@ package org.springframework.messaging.core;
 
 import java.util.Map;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.Message;
 import org.springframework.util.Assert;
 
@@ -42,8 +43,7 @@ public abstract class AbstractDestinationResolvingMessagingTemplate<D> extends A
 		DestinationResolvingMessageReceivingOperations<D>,
 		DestinationResolvingMessageRequestReplyOperations<D> {
 
-	@Nullable
-	private DestinationResolver<D> destinationResolver;
+	private @Nullable DestinationResolver<D> destinationResolver;
 
 
 	/**
@@ -60,8 +60,7 @@ public abstract class AbstractDestinationResolvingMessagingTemplate<D> extends A
 	/**
 	 * Return the configured destination resolver.
 	 */
-	@Nullable
-	public DestinationResolver<D> getDestinationResolver() {
+	public @Nullable DestinationResolver<D> getDestinationResolver() {
 		return this.destinationResolver;
 	}
 
@@ -102,36 +101,31 @@ public abstract class AbstractDestinationResolvingMessagingTemplate<D> extends A
 	}
 
 	@Override
-	@Nullable
-	public Message<?> receive(String destinationName) {
+	public @Nullable Message<?> receive(String destinationName) {
 		D destination = resolveDestination(destinationName);
 		return super.receive(destination);
 	}
 
 	@Override
-	@Nullable
-	public <T> T receiveAndConvert(String destinationName, Class<T> targetClass) {
+	public <T> @Nullable T receiveAndConvert(String destinationName, Class<T> targetClass) {
 		D destination = resolveDestination(destinationName);
 		return super.receiveAndConvert(destination, targetClass);
 	}
 
 	@Override
-	@Nullable
-	public Message<?> sendAndReceive(String destinationName, Message<?> requestMessage) {
+	public @Nullable Message<?> sendAndReceive(String destinationName, Message<?> requestMessage) {
 		D destination = resolveDestination(destinationName);
 		return super.sendAndReceive(destination, requestMessage);
 	}
 
 	@Override
-	@Nullable
-	public <T> T convertSendAndReceive(String destinationName, Object request, Class<T> targetClass) {
+	public <T> @Nullable T convertSendAndReceive(String destinationName, Object request, Class<T> targetClass) {
 		D destination = resolveDestination(destinationName);
 		return super.convertSendAndReceive(destination, request, targetClass);
 	}
 
 	@Override
-	@Nullable
-	public <T> T convertSendAndReceive(String destinationName, Object request,
+	public <T> @Nullable T convertSendAndReceive(String destinationName, Object request,
 			@Nullable Map<String, Object> headers, Class<T> targetClass) {
 
 		D destination = resolveDestination(destinationName);
@@ -139,8 +133,7 @@ public abstract class AbstractDestinationResolvingMessagingTemplate<D> extends A
 	}
 
 	@Override
-	@Nullable
-	public <T> T convertSendAndReceive(String destinationName, Object request, Class<T> targetClass,
+	public <T> @Nullable T convertSendAndReceive(String destinationName, Object request, Class<T> targetClass,
 			@Nullable MessagePostProcessor postProcessor) {
 
 		D destination = resolveDestination(destinationName);
@@ -148,8 +141,7 @@ public abstract class AbstractDestinationResolvingMessagingTemplate<D> extends A
 	}
 
 	@Override
-	@Nullable
-	public <T> T convertSendAndReceive(String destinationName, Object request,
+	public <T> @Nullable T convertSendAndReceive(String destinationName, Object request,
 			@Nullable Map<String, Object> headers, Class<T> targetClass,
 			@Nullable MessagePostProcessor postProcessor) {
 

spring-messaging/src/main/java/org/springframework/messaging/core/AbstractMessageReceivingTemplate.java

@@ -16,7 +16,8 @@
 
 package org.springframework.messaging.core;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.Message;
 import org.springframework.messaging.converter.MessageConversionException;
 import org.springframework.messaging.converter.MessageConverter;
@@ -35,14 +36,12 @@ public abstract class AbstractMessageReceivingTemplate<D> extends AbstractMessag
 		implements MessageReceivingOperations<D> {
 
 	@Override
-	@Nullable
-	public Message<?> receive() {
+	public @Nullable Message<?> receive() {
 		return doReceive(getRequiredDefaultDestination());
 	}
 
 	@Override
-	@Nullable
-	public Message<?> receive(D destination) {
+	public @Nullable Message<?> receive(D destination) {
 		return doReceive(destination);
 	}
 
@@ -52,19 +51,16 @@ public abstract class AbstractMessageReceivingTemplate<D> extends AbstractMessag
 	 * @return the received message, possibly {@code null} if the message could not
 	 * be received, for example due to a timeout
 	 */
-	@Nullable
-	protected abstract Message<?> doReceive(D destination);
+	protected abstract @Nullable Message<?> doReceive(D destination);
 
 
 	@Override
-	@Nullable
-	public <T> T receiveAndConvert(Class<T> targetClass) {
+	public <T> @Nullable T receiveAndConvert(Class<T> targetClass) {
 		return receiveAndConvert(getRequiredDefaultDestination(), targetClass);
 	}
 
 	@Override
-	@Nullable
-	public <T> T receiveAndConvert(D destination, Class<T> targetClass) {
+	public <T> @Nullable T receiveAndConvert(D destination, Class<T> targetClass) {
 		Message<?> message = doReceive(destination);
 		if (message != null) {
 			return doConvert(message, targetClass);
@@ -81,8 +77,7 @@ public abstract class AbstractMessageReceivingTemplate<D> extends AbstractMessag
 	 * @return the converted payload of the reply message (never {@code null})
 	 */
 	@SuppressWarnings("unchecked")
-	@Nullable
-	protected <T> T doConvert(Message<?> message, Class<T> targetClass) {
+	protected <T> @Nullable T doConvert(Message<?> message, Class<T> targetClass) {
 		MessageConverter messageConverter = getMessageConverter();
 		T value = (T) messageConverter.fromMessage(message, targetClass);
 		if (value == null) {

spring-messaging/src/main/java/org/springframework/messaging/core/AbstractMessageSendingTemplate.java

@@ -20,8 +20,8 @@ import java.util.Map;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHeaders;
 import org.springframework.messaging.MessagingException;
@@ -53,8 +53,7 @@ public abstract class AbstractMessageSendingTemplate<D> implements MessageSendin
 
 	protected final Log logger = LogFactory.getLog(getClass());
 
-	@Nullable
-	private D defaultDestination;
+	private @Nullable D defaultDestination;
 
 	private MessageConverter converter = new SimpleMessageConverter();
 
@@ -71,8 +70,7 @@ public abstract class AbstractMessageSendingTemplate<D> implements MessageSendin
 	/**
 	 * Return the configured default destination.
 	 */
-	@Nullable
-	public D getDefaultDestination() {
+	public @Nullable D getDefaultDestination() {
 		return this.defaultDestination;
 	}
 
@@ -194,8 +192,7 @@ public abstract class AbstractMessageSendingTemplate<D> implements MessageSendin
 	 * @param headers the headers to send (or {@code null} if none)
 	 * @return the actual headers to send (or {@code null} if none)
 	 */
-	@Nullable
-	protected Map<String, Object> processHeadersToSend(@Nullable Map<String, Object> headers) {
+	protected @Nullable Map<String, Object> processHeadersToSend(@Nullable Map<String, Object> headers) {
 		return headers;
 	}
 

spring-messaging/src/main/java/org/springframework/messaging/core/AbstractMessagingTemplate.java

@@ -18,7 +18,8 @@ package org.springframework.messaging.core;
 
 import java.util.Map;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.Message;
 
 /**
@@ -35,52 +36,44 @@ public abstract class AbstractMessagingTemplate<D> extends AbstractMessageReceiv
 		implements MessageRequestReplyOperations<D> {
 
 	@Override
-	@Nullable
-	public Message<?> sendAndReceive(Message<?> requestMessage) {
+	public @Nullable Message<?> sendAndReceive(Message<?> requestMessage) {
 		return sendAndReceive(getRequiredDefaultDestination(), requestMessage);
 	}
 
 	@Override
-	@Nullable
-	public Message<?> sendAndReceive(D destination, Message<?> requestMessage) {
+	public @Nullable Message<?> sendAndReceive(D destination, Message<?> requestMessage) {
 		return doSendAndReceive(destination, requestMessage);
 	}
 
-	@Nullable
-	protected abstract Message<?> doSendAndReceive(D destination, Message<?> requestMessage);
+	protected abstract @Nullable Message<?> doSendAndReceive(D destination, Message<?> requestMessage);
 
 
 	@Override
-	@Nullable
-	public <T> T convertSendAndReceive(Object request, Class<T> targetClass) {
+	public <T> @Nullable T convertSendAndReceive(Object request, Class<T> targetClass) {
 		return convertSendAndReceive(getRequiredDefaultDestination(), request, targetClass);
 	}
 
 	@Override
-	@Nullable
-	public <T> T convertSendAndReceive(D destination, Object request, Class<T> targetClass) {
+	public <T> @Nullable T convertSendAndReceive(D destination, Object request, Class<T> targetClass) {
 		return convertSendAndReceive(destination, request, null, targetClass);
 	}
 
 	@Override
-	@Nullable
-	public <T> T convertSendAndReceive(
+	public <T> @Nullable T convertSendAndReceive(
 			D destination, Object request, @Nullable Map<String, Object> headers, Class<T> targetClass) {
 
 		return convertSendAndReceive(destination, request, headers, targetClass, null);
 	}
 
 	@Override
-	@Nullable
-	public <T> T convertSendAndReceive(
+	public <T> @Nullable T convertSendAndReceive(
 			Object request, Class<T> targetClass, @Nullable MessagePostProcessor postProcessor) {
 
 		return convertSendAndReceive(getRequiredDefaultDestination(), request, targetClass, postProcessor);
 	}
 
 	@Override
-	@Nullable
-	public <T> T convertSendAndReceive(D destination, Object request, Class<T> targetClass,
+	public <T> @Nullable T convertSendAndReceive(D destination, Object request, Class<T> targetClass,
 			@Nullable MessagePostProcessor postProcessor) {
 
 		return convertSendAndReceive(destination, request, null, targetClass, postProcessor);
@@ -88,8 +81,7 @@ public abstract class AbstractMessagingTemplate<D> extends AbstractMessageReceiv
 
 	@SuppressWarnings("unchecked")
 	@Override
-	@Nullable
-	public <T> T convertSendAndReceive(D destination, Object request, @Nullable Map<String, Object> headers,
+	public <T> @Nullable T convertSendAndReceive(D destination, Object request, @Nullable Map<String, Object> headers,
 			Class<T> targetClass, @Nullable MessagePostProcessor postProcessor) {
 
 		Message<?> requestMessage = doConvert(request, headers, postProcessor);

spring-messaging/src/main/java/org/springframework/messaging/core/BeanFactoryMessageChannelDestinationResolver.java

@@ -16,10 +16,11 @@
 
 package org.springframework.messaging.core;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.BeanFactoryAware;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.MessageChannel;
 import org.springframework.util.Assert;
 
@@ -34,8 +35,7 @@ import org.springframework.util.Assert;
 public class BeanFactoryMessageChannelDestinationResolver
 		implements DestinationResolver<MessageChannel>, BeanFactoryAware {
 
-	@Nullable
-	private BeanFactory beanFactory;
+	private @Nullable BeanFactory beanFactory;
 
 
 	/**

spring-messaging/src/main/java/org/springframework/messaging/core/CachingDestinationResolverProxy.java

@@ -19,8 +19,9 @@ package org.springframework.messaging.core;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.beans.factory.InitializingBean;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -39,8 +40,7 @@ public class CachingDestinationResolverProxy<D> implements DestinationResolver<D
 
 	private final Map<String, D> resolvedDestinationCache = new ConcurrentHashMap<>();
 
-	@Nullable
-	private DestinationResolver<D> targetDestinationResolver;
+	private @Nullable DestinationResolver<D> targetDestinationResolver;
 
 
 	/**

spring-messaging/src/main/java/org/springframework/messaging/core/DestinationResolutionException.java

@@ -16,7 +16,8 @@
 
 package org.springframework.messaging.core;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.MessagingException;
 
 /**

spring-messaging/src/main/java/org/springframework/messaging/core/DestinationResolvingMessageReceivingOperations.java

@@ -16,7 +16,8 @@
 
 package org.springframework.messaging.core;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessagingException;
 
@@ -36,8 +37,7 @@ public interface DestinationResolvingMessageReceivingOperations<D> extends Messa
 	 * Resolve the given destination name and receive a message from it.
 	 * @param destinationName the destination name to resolve
 	 */
-	@Nullable
-	Message<?> receive(String destinationName) throws MessagingException;
+	@Nullable Message<?> receive(String destinationName) throws MessagingException;
 
 	/**
 	 * Resolve the given destination name, receive a message from it,
@@ -45,7 +45,6 @@ public interface DestinationResolvingMessageReceivingOperations<D> extends Messa
 	 * @param destinationName the destination name to resolve
 	 * @param targetClass the target class for the converted payload
 	 */
-	@Nullable
-	<T> T receiveAndConvert(String destinationName, Class<T> targetClass) throws MessagingException;
+	<T> @Nullable T receiveAndConvert(String destinationName, Class<T> targetClass) throws MessagingException;
 
 }

spring-messaging/src/main/java/org/springframework/messaging/core/DestinationResolvingMessageRequestReplyOperations.java

@@ -18,7 +18,8 @@ package org.springframework.messaging.core;
 
 import java.util.Map;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessagingException;
 
@@ -42,8 +43,7 @@ public interface DestinationResolvingMessageRequestReplyOperations<D> extends Me
 	 * @return the received message, possibly {@code null} if the message could not
 	 * be received, for example due to a timeout
 	 */
-	@Nullable
-	Message<?> sendAndReceive(String destinationName, Message<?> requestMessage) throws MessagingException;
+	@Nullable Message<?> sendAndReceive(String destinationName, Message<?> requestMessage) throws MessagingException;
 
 	/**
 	 * Resolve the given destination name, convert the payload request Object
@@ -57,8 +57,7 @@ public interface DestinationResolvingMessageRequestReplyOperations<D> extends Me
 	 * @return the converted payload of the reply message, possibly {@code null} if
 	 * the message could not be received, for example due to a timeout
 	 */
-	@Nullable
-	<T> T convertSendAndReceive(String destinationName, Object request, Class<T> targetClass)
+	<T> @Nullable T convertSendAndReceive(String destinationName, Object request, Class<T> targetClass)
 			throws MessagingException;
 
 	/**
@@ -74,8 +73,7 @@ public interface DestinationResolvingMessageRequestReplyOperations<D> extends Me
 	 * @return the converted payload of the reply message, possibly {@code null} if
 	 * the message could not be received, for example due to a timeout
 	 */
-	@Nullable
-	<T> T convertSendAndReceive(String destinationName, Object request,
+	<T> @Nullable T convertSendAndReceive(String destinationName, Object request,
 			@Nullable Map<String, Object> headers, Class<T> targetClass) throws MessagingException;
 
 	/**
@@ -92,8 +90,7 @@ public interface DestinationResolvingMessageRequestReplyOperations<D> extends Me
 	 * @return the converted payload of the reply message, possibly {@code null} if
 	 * the message could not be received, for example due to a timeout
 	 */
-	@Nullable
-	<T> T convertSendAndReceive(String destinationName, Object request, Class<T> targetClass,
+	<T> @Nullable T convertSendAndReceive(String destinationName, Object request, Class<T> targetClass,
 			@Nullable MessagePostProcessor requestPostProcessor) throws MessagingException;
 
 	/**
@@ -111,8 +108,7 @@ public interface DestinationResolvingMessageRequestReplyOperations<D> extends Me
 	 * @return the converted payload of the reply message, possibly {@code null} if
 	 * the message could not be received, for example due to a timeout
 	 */
-	@Nullable
-	<T> T convertSendAndReceive(String destinationName, Object request, @Nullable Map<String, Object> headers,
+	<T> @Nullable T convertSendAndReceive(String destinationName, Object request, @Nullable Map<String, Object> headers,
 			Class<T> targetClass, @Nullable MessagePostProcessor requestPostProcessor) throws MessagingException;
 
 }

spring-messaging/src/main/java/org/springframework/messaging/core/DestinationResolvingMessageSendingOperations.java

@@ -18,7 +18,8 @@ package org.springframework.messaging.core;
 
 import java.util.Map;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessagingException;
 

spring-messaging/src/main/java/org/springframework/messaging/core/GenericMessagingTemplate.java

@@ -21,11 +21,11 @@ import java.util.concurrent.TimeUnit;
 
 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;
 import org.springframework.beans.factory.BeanFactoryAware;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageChannel;
 import org.springframework.messaging.MessageDeliveryException;
@@ -193,13 +193,11 @@ public class GenericMessagingTemplate extends AbstractDestinationResolvingMessag
 	}
 
 	@Override
-	@Nullable
-	protected final Message<?> doReceive(MessageChannel channel) {
+	protected final @Nullable Message<?> doReceive(MessageChannel channel) {
 		return doReceive(channel, this.receiveTimeout);
 	}
 
-	@Nullable
-	protected final Message<?> doReceive(MessageChannel channel, long timeout) {
+	protected final @Nullable Message<?> doReceive(MessageChannel channel, long timeout) {
 		Assert.notNull(channel, "MessageChannel is required");
 		if (!(channel instanceof PollableChannel pollableChannel)) {
 			throw new IllegalStateException("A PollableChannel is required to receive messages");
@@ -215,8 +213,7 @@ public class GenericMessagingTemplate extends AbstractDestinationResolvingMessag
 	}
 
 	@Override
-	@Nullable
-	protected final Message<?> doSendAndReceive(MessageChannel channel, Message<?> requestMessage) {
+	protected final @Nullable Message<?> doSendAndReceive(MessageChannel channel, Message<?> requestMessage) {
 		Assert.notNull(channel, "'channel' is required");
 		Object originalReplyChannelHeader = requestMessage.getHeaders().getReplyChannel();
 		Object originalErrorChannelHeader = requestMessage.getHeaders().getErrorChannel();
@@ -259,8 +256,7 @@ public class GenericMessagingTemplate extends AbstractDestinationResolvingMessag
 		return (receiveTimeout != null ? receiveTimeout : this.receiveTimeout);
 	}
 
-	@Nullable
-	private Long headerToLong(@Nullable Object headerValue) {
+	private @Nullable Long headerToLong(@Nullable Object headerValue) {
 		if (headerValue instanceof Number number) {
 			return number.longValue();
 		}
@@ -284,8 +280,7 @@ public class GenericMessagingTemplate extends AbstractDestinationResolvingMessag
 
 		private final boolean throwExceptionOnLateReply;
 
-		@Nullable
-		private volatile Message<?> replyMessage;
+		private volatile @Nullable Message<?> replyMessage;
 
 		private volatile boolean hasReceived;
 
@@ -302,14 +297,12 @@ public class GenericMessagingTemplate extends AbstractDestinationResolvingMessag
 		}
 
 		@Override
-		@Nullable
-		public Message<?> receive() {
+		public @Nullable Message<?> receive() {
 			return this.receive(-1);
 		}
 
 		@Override
-		@Nullable
-		public Message<?> receive(long timeout) {
+		public @Nullable Message<?> receive(long timeout) {
 			try {
 				if (timeout < 0) {
 					this.replyLatch.await();

spring-messaging/src/main/java/org/springframework/messaging/core/MessageReceivingOperations.java

@@ -16,7 +16,8 @@
 
 package org.springframework.messaging.core;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessagingException;
 
@@ -36,8 +37,7 @@ public interface MessageReceivingOperations<D> {
 	 * @return the received message, possibly {@code null} if the message could not
 	 * be received, for example due to a timeout
 	 */
-	@Nullable
-	Message<?> receive() throws MessagingException;
+	@Nullable Message<?> receive() throws MessagingException;
 
 	/**
 	 * Receive a message from the given destination.
@@ -45,8 +45,7 @@ public interface MessageReceivingOperations<D> {
 	 * @return the received message, possibly {@code null} if the message could not
 	 * be received, for example due to a timeout
 	 */
-	@Nullable
-	Message<?> receive(D destination) throws MessagingException;
+	@Nullable Message<?> receive(D destination) throws MessagingException;
 
 	/**
 	 * Receive a message from a default destination and convert its payload to the
@@ -55,8 +54,7 @@ public interface MessageReceivingOperations<D> {
 	 * @return the converted payload of the reply message, possibly {@code null} if
 	 * the message could not be received, for example due to a timeout
 	 */
-	@Nullable
-	<T> T receiveAndConvert(Class<T> targetClass) throws MessagingException;
+	<T> @Nullable T receiveAndConvert(Class<T> targetClass) throws MessagingException;
 
 	/**
 	 * Receive a message from the given destination and convert its payload to the
@@ -66,7 +64,6 @@ public interface MessageReceivingOperations<D> {
 	 * @return the converted payload of the reply message, possibly {@code null} if
 	 * the message could not be received, for example due to a timeout
 	 */
-	@Nullable
-	<T> T receiveAndConvert(D destination, Class<T> targetClass) throws MessagingException;
+	<T> @Nullable T receiveAndConvert(D destination, Class<T> targetClass) throws MessagingException;
 
 }

spring-messaging/src/main/java/org/springframework/messaging/core/MessageRequestReplyOperations.java

@@ -18,7 +18,8 @@ package org.springframework.messaging.core;
 
 import java.util.Map;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessagingException;
 
@@ -39,8 +40,7 @@ public interface MessageRequestReplyOperations<D> {
 	 * @return the reply, possibly {@code null} if the message could not be received,
 	 * for example due to a timeout
 	 */
-	@Nullable
-	Message<?> sendAndReceive(Message<?> requestMessage) throws MessagingException;
+	@Nullable Message<?> sendAndReceive(Message<?> requestMessage) throws MessagingException;
 
 	/**
 	 * Send a request message and receive the reply from the given destination.
@@ -49,8 +49,7 @@ public interface MessageRequestReplyOperations<D> {
 	 * @return the reply, possibly {@code null} if the message could not be received,
 	 * for example due to a timeout
 	 */
-	@Nullable
-	Message<?> sendAndReceive(D destination, Message<?> requestMessage) throws MessagingException;
+	@Nullable Message<?> sendAndReceive(D destination, Message<?> requestMessage) throws MessagingException;
 
 	/**
 	 * Convert the given request Object to serialized form, possibly using a
@@ -62,8 +61,7 @@ public interface MessageRequestReplyOperations<D> {
 	 * @return the payload of the reply message, possibly {@code null} if the message
 	 * could not be received, for example due to a timeout
 	 */
-	@Nullable
-	<T> T convertSendAndReceive(Object request, Class<T> targetClass) throws MessagingException;
+	<T> @Nullable T convertSendAndReceive(Object request, Class<T> targetClass) throws MessagingException;
 
 	/**
 	 * Convert the given request Object to serialized form, possibly using a
@@ -76,8 +74,7 @@ public interface MessageRequestReplyOperations<D> {
 	 * @return the payload of the reply message, possibly {@code null} if the message
 	 * could not be received, for example due to a timeout
 	 */
-	@Nullable
-	<T> T convertSendAndReceive(D destination, Object request, Class<T> targetClass) throws MessagingException;
+	<T> @Nullable T convertSendAndReceive(D destination, Object request, Class<T> targetClass) throws MessagingException;
 
 	/**
 	 * Convert the given request Object to serialized form, possibly using a
@@ -91,8 +88,7 @@ public interface MessageRequestReplyOperations<D> {
 	 * @return the payload of the reply message, possibly {@code null} if the message
 	 * could not be received, for example due to a timeout
 	 */
-	@Nullable
-	<T> T convertSendAndReceive(
+	<T> @Nullable T convertSendAndReceive(
 			D destination, Object request, @Nullable Map<String, Object> headers, Class<T> targetClass)
 			throws MessagingException;
 
@@ -108,8 +104,7 @@ public interface MessageRequestReplyOperations<D> {
 	 * @return the payload of the reply message, possibly {@code null} if the message
 	 * could not be received, for example due to a timeout
 	 */
-	@Nullable
-	<T> T convertSendAndReceive(
+	<T> @Nullable T convertSendAndReceive(
 			Object request, Class<T> targetClass, @Nullable MessagePostProcessor requestPostProcessor)
 			throws MessagingException;
 
@@ -126,8 +121,7 @@ public interface MessageRequestReplyOperations<D> {
 	 * @return the payload of the reply message, possibly {@code null} if the message
 	 * could not be received, for example due to a timeout
 	 */
-	@Nullable
-	<T> T convertSendAndReceive(D destination, Object request, Class<T> targetClass,
+	<T> @Nullable T convertSendAndReceive(D destination, Object request, Class<T> targetClass,
 			MessagePostProcessor requestPostProcessor) throws MessagingException;
 
 	/**
@@ -143,8 +137,7 @@ public interface MessageRequestReplyOperations<D> {
 	 * @return the payload of the reply message, possibly {@code null} if the message
 	 * could not be received, for example due to a timeout
 	 */
-	@Nullable
-	<T> T convertSendAndReceive(
+	<T> @Nullable T convertSendAndReceive(
 			D destination, Object request, @Nullable Map<String, Object> headers, Class<T> targetClass,
 			@Nullable MessagePostProcessor requestPostProcessor) throws MessagingException;
 

spring-messaging/src/main/java/org/springframework/messaging/core/MessageSendingOperations.java

@@ -18,7 +18,8 @@ package org.springframework.messaging.core;
 
 import java.util.Map;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessagingException;
 

spring-messaging/src/main/java/org/springframework/messaging/core/package-info.java

@@ -1,9 +1,7 @@
 /**
  * Defines interfaces and implementation classes for messaging templates.
  */
-@NonNullApi
-@NonNullFields
+@NullMarked
 package org.springframework.messaging.core;
 
-import org.springframework.lang.NonNullApi;
-import org.springframework.lang.NonNullFields;
+import org.jspecify.annotations.NullMarked;

spring-messaging/src/main/java/org/springframework/messaging/handler/AbstractMessageCondition.java

@@ -19,7 +19,7 @@ package org.springframework.messaging.handler;
 import java.util.Collection;
 import java.util.StringJoiner;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Base class for {@code MessageCondition's} that pre-declares abstract methods

spring-messaging/src/main/java/org/springframework/messaging/handler/CompositeMessageCondition.java

@@ -21,7 +21,8 @@ import java.util.Arrays;
 import java.util.List;
 import java.util.stream.Collectors;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.Message;
 import org.springframework.util.Assert;
 
@@ -80,8 +81,7 @@ public class CompositeMessageCondition implements MessageCondition<CompositeMess
 	}
 
 	@Override
-	@Nullable
-	public CompositeMessageCondition getMatchingCondition(Message<?> message) {
+	public @Nullable CompositeMessageCondition getMatchingCondition(Message<?> message) {
 		List<MessageCondition<?>> result = new ArrayList<>(this.messageConditions.size());
 		for (MessageCondition<?> condition : this.messageConditions) {
 			MessageCondition<?> matchingCondition = (MessageCondition<?>) condition.getMatchingCondition(message);

spring-messaging/src/main/java/org/springframework/messaging/handler/DestinationPatternsMessageCondition.java

@@ -25,7 +25,8 @@ import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.Message;
 import org.springframework.util.AntPathMatcher;
 import org.springframework.util.CollectionUtils;
@@ -160,8 +161,7 @@ public class DestinationPatternsMessageCondition
 	 * or {@code null} either if a destination can not be extracted or there is no match
 	 */
 	@Override
-	@Nullable
-	public DestinationPatternsMessageCondition getMatchingCondition(Message<?> message) {
+	public @Nullable DestinationPatternsMessageCondition getMatchingCondition(Message<?> message) {
 		Object destination = message.getHeaders().get(LOOKUP_DESTINATION_HEADER);
 		if (destination == null) {
 			return null;

spring-messaging/src/main/java/org/springframework/messaging/handler/HandlerMethod.java

@@ -22,10 +22,10 @@ import java.util.stream.IntStream;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.core.annotation.AnnotatedMethod;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 
@@ -53,13 +53,11 @@ public class HandlerMethod extends AnnotatedMethod {
 
 	private final Object bean;
 
-	@Nullable
-	private final BeanFactory beanFactory;
+	private final @Nullable BeanFactory beanFactory;
 
 	private final Class<?> beanType;
 
-	@Nullable
-	private HandlerMethod resolvedFromHandlerMethod;
+	private @Nullable HandlerMethod resolvedFromHandlerMethod;
 
 	protected Log logger = defaultLogger;
 
@@ -167,8 +165,7 @@ public class HandlerMethod extends AnnotatedMethod {
 	 * resolved via {@link #createWithResolvedBean()}.
 	 * @since 4.3
 	 */
-	@Nullable
-	public HandlerMethod getResolvedFromHandlerMethod() {
+	public @Nullable HandlerMethod getResolvedFromHandlerMethod() {
 		return this.resolvedFromHandlerMethod;
 	}
 
@@ -215,7 +212,7 @@ public class HandlerMethod extends AnnotatedMethod {
 	 * beans, and others). Endpoint classes that require proxying should prefer
 	 * class-based proxy mechanisms.
 	 */
-	protected void assertTargetBean(Method method, Object targetBean, Object[] args) {
+	protected void assertTargetBean(Method method, Object targetBean, @Nullable Object[] args) {
 		Class<?> methodDeclaringClass = method.getDeclaringClass();
 		Class<?> targetBeanClass = targetBean.getClass();
 		if (!methodDeclaringClass.isAssignableFrom(targetBeanClass)) {
@@ -227,7 +224,7 @@ public class HandlerMethod extends AnnotatedMethod {
 		}
 	}
 
-	protected String formatInvokeError(String text, Object[] args) {
+	protected String formatInvokeError(String text, @Nullable Object[] args) {
 		String formattedArgs = IntStream.range(0, args.length)
 				.mapToObj(i -> (args[i] != null ?
 						"[" + i + "] [type=" + args[i].getClass().getName() + "] [value=" + args[i] + "]" :

spring-messaging/src/main/java/org/springframework/messaging/handler/MessageCondition.java

@@ -16,7 +16,8 @@
 
 package org.springframework.messaging.handler;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.messaging.Message;
 
 /**
@@ -47,8 +48,7 @@ public interface MessageCondition<T> {
 	 * condition with sorted, matching patterns only.
 	 * @return a condition instance in case of a match; or {@code null} if there is no match.
 	 */
-	@Nullable
-	T getMatchingCondition(Message<?> message);
+	@Nullable T getMatchingCondition(Message<?> message);
 
 	/**
 	 * Compare this condition to another in the context of a specific message.

spring-messaging/src/main/java/org/springframework/messaging/handler/MessagingAdviceBean.java

@@ -16,8 +16,9 @@
 
 package org.springframework.messaging.handler;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.Ordered;
-import org.springframework.lang.Nullable;
 
 /**
  * Represents a Spring-managed bean with cross-cutting functionality to be
@@ -40,8 +41,7 @@ public interface MessagingAdviceBean extends Ordered {
 	 * <p>If the bean type is a CGLIB-generated class, the original user-defined
 	 * class is returned.
 	 */
-	@Nullable
-	Class<?> getBeanType();
+	@Nullable Class<?> getBeanType();
 
 	/**
 	 * Return the advice bean instance, if necessary resolving a bean specified

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/MessageMappingReflectiveProcessor.java

@@ -22,12 +22,13 @@ import java.lang.reflect.Parameter;
 import java.lang.reflect.Type;
 import java.security.Principal;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.aot.hint.BindingReflectionHintsRegistrar;
 import org.springframework.aot.hint.ExecutableMode;
 import org.springframework.aot.hint.ReflectionHints;
 import org.springframework.aot.hint.annotation.ReflectiveProcessor;
 import org.springframework.core.MethodParameter;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHeaders;
 import org.springframework.messaging.support.MessageHeaderAccessor;
@@ -114,8 +115,7 @@ public class MessageMappingReflectiveProcessor implements ReflectiveProcessor {
 		this.bindingRegistrar.registerReflectionHints(hints, returnType.getGenericParameterType());
 	}
 
-	@Nullable
-	protected Type getMessageType(MethodParameter parameter) {
+	protected @Nullable Type getMessageType(MethodParameter parameter) {
 		MethodParameter nestedParameter = parameter.nested();
 		return (nestedParameter.getNestedParameterType() == nestedParameter.getParameterType() ?
 				null : nestedParameter.getNestedParameterType());

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/package-info.java

@@ -1,9 +1,7 @@
 /**
  * Annotations and support classes for handling messages.
  */
-@NonNullApi
-@NonNullFields
+@NullMarked
 package org.springframework.messaging.handler.annotation;
 
-import org.springframework.lang.NonNullApi;
-import org.springframework.lang.NonNullFields;
+import org.jspecify.annotations.NullMarked;

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/reactive/AbstractNamedValueMethodArgumentResolver.java

@@ -19,6 +19,8 @@ package org.springframework.messaging.handler.annotation.reactive;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.config.BeanExpressionContext;
 import org.springframework.beans.factory.config.BeanExpressionResolver;
@@ -26,7 +28,6 @@ import org.springframework.beans.factory.config.ConfigurableBeanFactory;
 import org.springframework.core.MethodParameter;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.TypeDescriptor;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.handler.annotation.ValueConstants;
 import org.springframework.messaging.handler.invocation.reactive.SyncHandlerMethodArgumentResolver;
@@ -55,11 +56,9 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements SyncHa
 
 	private final ConversionService conversionService;
 
-	@Nullable
-	private final ConfigurableBeanFactory configurableBeanFactory;
+	private final @Nullable ConfigurableBeanFactory configurableBeanFactory;
 
-	@Nullable
-	private final BeanExpressionContext expressionContext;
+	private final @Nullable BeanExpressionContext expressionContext;
 
 	private final Map<MethodParameter, NamedValueInfo> namedValueInfoCache = new ConcurrentHashMap<>(256);
 
@@ -81,8 +80,7 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements SyncHa
 
 
 	@Override
-	@Nullable
-	public Object resolveArgumentValue(MethodParameter parameter, Message<?> message) {
+	public @Nullable Object resolveArgumentValue(MethodParameter parameter, Message<?> message) {
 		NamedValueInfo namedValueInfo = getNamedValueInfo(parameter);
 		MethodParameter nestedParameter = parameter.nestedIfOptional();
 
@@ -167,8 +165,7 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements SyncHa
 	 * Resolve the given annotation-specified value,
 	 * potentially containing placeholders and expressions.
 	 */
-	@Nullable
-	private Object resolveEmbeddedValuesAndExpressions(String value) {
+	private @Nullable Object resolveEmbeddedValuesAndExpressions(String value) {
 		if (this.configurableBeanFactory == null || this.expressionContext == null) {
 			return value;
 		}
@@ -187,8 +184,7 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements SyncHa
 	 * @param name the name of the value being resolved
 	 * @return the resolved argument. May be {@code null}
 	 */
-	@Nullable
-	protected abstract Object resolveArgumentInternal(MethodParameter parameter, Message<?> message, String name);
+	protected abstract @Nullable Object resolveArgumentInternal(MethodParameter parameter, Message<?> message, String name);
 
 	/**
 	 * Invoked when a value is required, but {@link #resolveArgumentInternal}
@@ -205,8 +201,7 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements SyncHa
 	 * Specifically for booleans method parameters, use {@link Boolean#FALSE}.
 	 * Also raise an ISE for primitive types.
 	 */
-	@Nullable
-	private Object handleNullValue(String name, @Nullable Object value, Class<?> paramType) {
+	private @Nullable Object handleNullValue(String name, @Nullable Object value, Class<?> paramType) {
 		if (value == null) {
 			if (paramType == boolean.class) {
 				return Boolean.FALSE;
@@ -231,8 +226,7 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements SyncHa
 
 		private final boolean required;
 
-		@Nullable
-		private final String defaultValue;
+		private final @Nullable String defaultValue;
 
 		protected NamedValueInfo(String name, boolean required, @Nullable String defaultValue) {
 			this.name = name;

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/reactive/DestinationVariableMethodArgumentResolver.java

@@ -18,9 +18,10 @@ package org.springframework.messaging.handler.annotation.reactive;
 
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.MethodParameter;
 import org.springframework.core.convert.ConversionService;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHandlingException;
 import org.springframework.messaging.MessageHeaders;
@@ -59,9 +60,8 @@ public class DestinationVariableMethodArgumentResolver extends AbstractNamedValu
 	}
 
 	@Override
-	@Nullable
 	@SuppressWarnings("unchecked")
-	protected Object resolveArgumentInternal(MethodParameter parameter, Message<?> message, String name) {
+	protected @Nullable Object resolveArgumentInternal(MethodParameter parameter, Message<?> message, String name) {
 		MessageHeaders headers = message.getHeaders();
 		Map<String, String> vars = (Map<String, String>) headers.get(DESTINATION_TEMPLATE_VARIABLES_HEADER);
 		return vars != null ? vars.get(name) : null;

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/reactive/HeaderMethodArgumentResolver.java

@@ -21,11 +21,11 @@ import java.util.Map;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.beans.factory.config.ConfigurableBeanFactory;
 import org.springframework.core.MethodParameter;
 import org.springframework.core.convert.ConversionService;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHandlingException;
 import org.springframework.messaging.handler.annotation.Header;
@@ -67,8 +67,7 @@ public class HeaderMethodArgumentResolver extends AbstractNamedValueMethodArgume
 	}
 
 	@Override
-	@Nullable
-	protected Object resolveArgumentInternal(MethodParameter parameter, Message<?> message, String name) {
+	protected @Nullable Object resolveArgumentInternal(MethodParameter parameter, Message<?> message, String name) {
 
 		Object headerValue = message.getHeaders().get(name);
 		Object nativeHeaderValue = getNativeHeaderValue(message, name);
@@ -84,8 +83,7 @@ public class HeaderMethodArgumentResolver extends AbstractNamedValueMethodArgume
 		return (headerValue != null ? headerValue : nativeHeaderValue);
 	}
 
-	@Nullable
-	private Object getNativeHeaderValue(Message<?> message, String name) {
+	private @Nullable Object getNativeHeaderValue(Message<?> message, String name) {
 		Map<String, List<String>> nativeHeaders = getNativeHeaders(message);
 		if (name.startsWith("nativeHeaders.")) {
 			name = name.substring("nativeHeaders.".length());
@@ -98,8 +96,7 @@ public class HeaderMethodArgumentResolver extends AbstractNamedValueMethodArgume
 	}
 
 	@SuppressWarnings("unchecked")
-	@Nullable
-	private Map<String, List<String>> getNativeHeaders(Message<?> message) {
+	private @Nullable Map<String, List<String>> getNativeHeaders(Message<?> message) {
 		return (Map<String, List<String>>) message.getHeaders().get(NativeMessageHeaderAccessor.NATIVE_HEADERS);
 	}
 

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/reactive/HeadersMethodArgumentResolver.java

@@ -19,8 +19,9 @@ package org.springframework.messaging.handler.annotation.reactive;
 import java.lang.reflect.Method;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.MethodParameter;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHeaders;
 import org.springframework.messaging.handler.annotation.Headers;
@@ -49,8 +50,7 @@ public class HeadersMethodArgumentResolver implements SyncHandlerMethodArgumentR
 	}
 
 	@Override
-	@Nullable
-	public Object resolveArgumentValue(MethodParameter parameter, Message<?> message) {
+	public @Nullable Object resolveArgumentValue(MethodParameter parameter, Message<?> message) {
 		Class<?> paramType = parameter.getParameterType();
 		if (Map.class.isAssignableFrom(paramType)) {
 			return message.getHeaders();

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/reactive/MessageMappingMessageHandler.java

@@ -28,6 +28,7 @@ import java.util.Map;
 import java.util.Set;
 import java.util.function.Predicate;
 
+import org.jspecify.annotations.Nullable;
 import reactor.core.publisher.Mono;
 
 import org.springframework.beans.factory.config.ConfigurableBeanFactory;
@@ -39,7 +40,6 @@ import org.springframework.core.annotation.AnnotatedElementUtils;
 import org.springframework.core.codec.Decoder;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.format.support.DefaultFormattingConversionService;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.handler.CompositeMessageCondition;
 import org.springframework.messaging.handler.DestinationPatternsMessageCondition;
@@ -86,16 +86,13 @@ public class MessageMappingMessageHandler extends AbstractMethodMessageHandler<C
 
 	private final List<Decoder<?>> decoders = new ArrayList<>();
 
-	@Nullable
-	private Validator validator;
+	private @Nullable Validator validator;
 
-	@Nullable
-	private RouteMatcher routeMatcher;
+	private @Nullable RouteMatcher routeMatcher;
 
 	private ConversionService conversionService = new DefaultFormattingConversionService();
 
-	@Nullable
-	private StringValueResolver valueResolver;
+	private @Nullable StringValueResolver valueResolver;
 
 
 	public MessageMappingMessageHandler() {
@@ -130,8 +127,7 @@ public class MessageMappingMessageHandler extends AbstractMethodMessageHandler<C
 	/**
 	 * Return the configured Validator instance.
 	 */
-	@Nullable
-	public Validator getValidator() {
+	public @Nullable Validator getValidator() {
 		return this.validator;
 	}
 
@@ -151,8 +147,7 @@ public class MessageMappingMessageHandler extends AbstractMethodMessageHandler<C
 	 * Return the {@code RouteMatcher} used to map messages to handlers.
 	 * May be {@code null} before the component is initialized.
 	 */
-	@Nullable
-	public RouteMatcher getRouteMatcher() {
+	public @Nullable RouteMatcher getRouteMatcher() {
 		return this.routeMatcher;
 	}
 
@@ -272,8 +267,7 @@ public class MessageMappingMessageHandler extends AbstractMethodMessageHandler<C
 
 
 	@Override
-	@Nullable
-	protected CompositeMessageCondition getMappingForMethod(Method method, Class<?> handlerType) {
+	protected @Nullable CompositeMessageCondition getMappingForMethod(Method method, Class<?> handlerType) {
 		CompositeMessageCondition methodCondition = getCondition(method);
 		if (methodCondition != null) {
 			CompositeMessageCondition typeCondition = getCondition(handlerType);
@@ -289,8 +283,7 @@ public class MessageMappingMessageHandler extends AbstractMethodMessageHandler<C
 	 * @param element the element to check
 	 * @return the condition, or {@code null}
 	 */
-	@Nullable
-	protected CompositeMessageCondition getCondition(AnnotatedElement element) {
+	protected @Nullable CompositeMessageCondition getCondition(AnnotatedElement element) {
 		MessageMapping ann = AnnotatedElementUtils.findMergedAnnotation(element, MessageMapping.class);
 		if (ann == null || ann.value().length == 0) {
 			return null;
@@ -326,15 +319,13 @@ public class MessageMappingMessageHandler extends AbstractMethodMessageHandler<C
 	}
 
 	@Override
-	@Nullable
-	protected RouteMatcher.Route getDestination(Message<?> message) {
+	protected RouteMatcher.@Nullable Route getDestination(Message<?> message) {
 		return (RouteMatcher.Route) message.getHeaders()
 				.get(DestinationPatternsMessageCondition.LOOKUP_DESTINATION_HEADER);
 	}
 
 	@Override
-	@Nullable
-	protected CompositeMessageCondition getMatchingMapping(CompositeMessageCondition mapping, Message<?> message) {
+	protected @Nullable CompositeMessageCondition getMatchingMapping(CompositeMessageCondition mapping, Message<?> message) {
 		return mapping.getMatchingCondition(message);
 	}
 

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/reactive/PayloadMethodArgumentResolver.java

@@ -24,6 +24,7 @@ import java.util.function.Consumer;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
@@ -37,7 +38,6 @@ import org.springframework.core.codec.Decoder;
 import org.springframework.core.codec.DecodingException;
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DataBufferUtils;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHeaders;
 import org.springframework.messaging.handler.annotation.Payload;
@@ -79,8 +79,7 @@ public class PayloadMethodArgumentResolver implements HandlerMethodArgumentResol
 
 	private final List<Decoder<?>> decoders;
 
-	@Nullable
-	private final Validator validator;
+	private final @Nullable Validator validator;
 
 	private final ReactiveAdapterRegistry adapterRegistry;
 
@@ -108,8 +107,7 @@ public class PayloadMethodArgumentResolver implements HandlerMethodArgumentResol
 	/**
 	 * Return the configured validator, if any.
 	 */
-	@Nullable
-	public Validator getValidator() {
+	public @Nullable Validator getValidator() {
 		return this.validator;
 	}
 
@@ -196,8 +194,7 @@ public class PayloadMethodArgumentResolver implements HandlerMethodArgumentResol
 	 * {@link MimeType} value or a String to parse to a {@link MimeType}.
 	 * @param message the input message
 	 */
-	@Nullable
-	protected MimeType getMimeType(Message<?> message) {
+	protected @Nullable MimeType getMimeType(Message<?> message) {
 		Object headerValue = message.getHeaders().get(MessageHeaders.CONTENT_TYPE);
 		if (headerValue == null) {
 			return null;
@@ -279,8 +276,7 @@ public class PayloadMethodArgumentResolver implements HandlerMethodArgumentResol
 				"Payload content is missing: " + param.getExecutable().toGenericString());
 	}
 
-	@Nullable
-	private Consumer<Object> getValidator(Message<?> message, MethodParameter parameter) {
+	private @Nullable Consumer<Object> getValidator(Message<?> message, MethodParameter parameter) {
 		if (this.validator == null) {
 			return null;
 		}

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/reactive/package-info.java

@@ -2,9 +2,7 @@
  * Support classes for working with annotated message-handling methods with
  * non-blocking, reactive contracts.
  */
-@NonNullApi
-@NonNullFields
+@NullMarked
 package org.springframework.messaging.handler.annotation.reactive;
 
-import org.springframework.lang.NonNullApi;
-import org.springframework.lang.NonNullFields;
+import org.jspecify.annotations.NullMarked;

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/AbstractNamedValueMethodArgumentResolver.java

@@ -19,6 +19,8 @@ package org.springframework.messaging.handler.annotation.support;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.config.BeanExpressionContext;
 import org.springframework.beans.factory.config.BeanExpressionResolver;
@@ -27,7 +29,6 @@ import org.springframework.core.MethodParameter;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.core.convert.support.DefaultConversionService;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.handler.annotation.ValueConstants;
 import org.springframework.messaging.handler.invocation.HandlerMethodArgumentResolver;
@@ -57,11 +58,9 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 
 	private final ConversionService conversionService;
 
-	@Nullable
-	private final ConfigurableBeanFactory configurableBeanFactory;
+	private final @Nullable ConfigurableBeanFactory configurableBeanFactory;
 
-	@Nullable
-	private final BeanExpressionContext expressionContext;
+	private final @Nullable BeanExpressionContext expressionContext;
 
 	private final Map<MethodParameter, NamedValueInfo> namedValueInfoCache = new ConcurrentHashMap<>(256);
 
@@ -89,8 +88,7 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 
 
 	@Override
-	@Nullable
-	public Object resolveArgument(MethodParameter parameter, Message<?> message) throws Exception {
+	public @Nullable Object resolveArgument(MethodParameter parameter, Message<?> message) throws Exception {
 		NamedValueInfo namedValueInfo = getNamedValueInfo(parameter);
 		MethodParameter nestedParameter = parameter.nestedIfOptional();
 
@@ -177,8 +175,7 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 	 * Resolve the given annotation-specified value,
 	 * potentially containing placeholders and expressions.
 	 */
-	@Nullable
-	private Object resolveEmbeddedValuesAndExpressions(String value) {
+	private @Nullable Object resolveEmbeddedValuesAndExpressions(String value) {
 		if (this.configurableBeanFactory == null || this.expressionContext == null) {
 			return value;
 		}
@@ -198,8 +195,7 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 	 * @return the resolved argument. May be {@code null}
 	 * @throws Exception in case of errors
 	 */
-	@Nullable
-	protected abstract Object resolveArgumentInternal(MethodParameter parameter, Message<?> message, String name)
+	protected abstract @Nullable Object resolveArgumentInternal(MethodParameter parameter, Message<?> message, String name)
 			throws Exception;
 
 	/**
@@ -217,8 +213,7 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 	 * Specifically for booleans method parameters, use {@link Boolean#FALSE}.
 	 * Also raise an ISE for primitive types.
 	 */
-	@Nullable
-	private Object handleNullValue(String name, @Nullable Object value, Class<?> paramType) {
+	private @Nullable Object handleNullValue(String name, @Nullable Object value, Class<?> paramType) {
 		if (value == null) {
 			if (paramType == boolean.class) {
 				return Boolean.FALSE;
@@ -254,8 +249,7 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 
 		private final boolean required;
 
-		@Nullable
-		private final String defaultValue;
+		private final @Nullable String defaultValue;
 
 		protected NamedValueInfo(String name, boolean required, @Nullable String defaultValue) {
 			this.name = name;

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/DefaultMessageHandlerMethodFactory.java

@@ -20,13 +20,14 @@ import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.BeanFactoryAware;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.beans.factory.config.ConfigurableBeanFactory;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.format.support.DefaultFormattingConversionService;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.converter.GenericMessageConverter;
 import org.springframework.messaging.converter.MessageConverter;
 import org.springframework.messaging.handler.invocation.HandlerMethodArgumentResolver;
@@ -62,20 +63,16 @@ public class DefaultMessageHandlerMethodFactory
 
 	private ConversionService conversionService = new DefaultFormattingConversionService();
 
-	@Nullable
-	private MessageConverter messageConverter;
+	private @Nullable MessageConverter messageConverter;
 
-	@Nullable
-	private Validator validator;
+	private @Nullable Validator validator;
 
-	@Nullable
-	private List<HandlerMethodArgumentResolver> customArgumentResolvers;
+	private @Nullable List<HandlerMethodArgumentResolver> customArgumentResolvers;
 
 	private final HandlerMethodArgumentResolverComposite argumentResolvers =
 			new HandlerMethodArgumentResolverComposite();
 
-	@Nullable
-	private BeanFactory beanFactory;
+	private @Nullable BeanFactory beanFactory;
 
 
 	/**

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/DestinationVariableMethodArgumentResolver.java

@@ -18,9 +18,10 @@ package org.springframework.messaging.handler.annotation.support;
 
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.MethodParameter;
 import org.springframework.core.convert.ConversionService;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHandlingException;
 import org.springframework.messaging.MessageHeaders;
@@ -59,9 +60,8 @@ public class DestinationVariableMethodArgumentResolver extends AbstractNamedValu
 	}
 
 	@Override
-	@Nullable
 	@SuppressWarnings("unchecked")
-	protected Object resolveArgumentInternal(MethodParameter parameter, Message<?> message, String name) {
+	protected @Nullable Object resolveArgumentInternal(MethodParameter parameter, Message<?> message, String name) {
 		MessageHeaders headers = message.getHeaders();
 		Map<String, String> vars = (Map<String, String>) headers.get(DESTINATION_TEMPLATE_VARIABLES_HEADER);
 		return vars != null ? vars.get(name) : null;

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/HeaderMethodArgumentResolver.java

@@ -21,11 +21,11 @@ import java.util.Map;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.beans.factory.config.ConfigurableBeanFactory;
 import org.springframework.core.MethodParameter;
 import org.springframework.core.convert.ConversionService;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHandlingException;
 import org.springframework.messaging.handler.annotation.Header;
@@ -68,8 +68,7 @@ public class HeaderMethodArgumentResolver extends AbstractNamedValueMethodArgume
 	}
 
 	@Override
-	@Nullable
-	protected Object resolveArgumentInternal(MethodParameter parameter, Message<?> message, String name)
+	protected @Nullable Object resolveArgumentInternal(MethodParameter parameter, Message<?> message, String name)
 			throws Exception {
 
 		Object headerValue = message.getHeaders().get(name);
@@ -86,8 +85,7 @@ public class HeaderMethodArgumentResolver extends AbstractNamedValueMethodArgume
 		return (headerValue != null ? headerValue : nativeHeaderValue);
 	}
 
-	@Nullable
-	private Object getNativeHeaderValue(Message<?> message, String name) {
+	private @Nullable Object getNativeHeaderValue(Message<?> message, String name) {
 		Map<String, List<String>> nativeHeaders = getNativeHeaders(message);
 		if (name.startsWith("nativeHeaders.")) {
 			name = name.substring("nativeHeaders.".length());
@@ -100,8 +98,7 @@ public class HeaderMethodArgumentResolver extends AbstractNamedValueMethodArgume
 	}
 
 	@SuppressWarnings("unchecked")
-	@Nullable
-	private Map<String, List<String>> getNativeHeaders(Message<?> message) {
+	private @Nullable Map<String, List<String>> getNativeHeaders(Message<?> message) {
 		return (Map<String, List<String>>) message.getHeaders().get(NativeMessageHeaderAccessor.NATIVE_HEADERS);
 	}
 

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/HeadersMethodArgumentResolver.java

@@ -19,8 +19,9 @@ package org.springframework.messaging.handler.annotation.support;
 import java.lang.reflect.Method;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.MethodParameter;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHeaders;
 import org.springframework.messaging.handler.annotation.Headers;
@@ -49,8 +50,7 @@ public class HeadersMethodArgumentResolver implements HandlerMethodArgumentResol
 	}
 
 	@Override
-	@Nullable
-	public Object resolveArgument(MethodParameter parameter, Message<?> message) throws Exception {
+	public @Nullable Object resolveArgument(MethodParameter parameter, Message<?> message) throws Exception {
 		Class<?> paramType = parameter.getParameterType();
 		if (Map.class.isAssignableFrom(paramType)) {
 			return message.getHeaders();

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/MessageMethodArgumentResolver.java

@@ -18,9 +18,10 @@ package org.springframework.messaging.handler.annotation.support;
 
 import java.lang.reflect.Type;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.MethodParameter;
 import org.springframework.core.ResolvableType;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.converter.MessageConversionException;
 import org.springframework.messaging.converter.MessageConverter;
@@ -43,8 +44,7 @@ import org.springframework.util.StringUtils;
  */
 public class MessageMethodArgumentResolver implements HandlerMethodArgumentResolver {
 
-	@Nullable
-	private final MessageConverter converter;
+	private final @Nullable MessageConverter converter;
 
 
 	/**

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/MethodArgumentNotValidException.java

@@ -16,8 +16,9 @@
 
 package org.springframework.messaging.handler.annotation.support;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.MethodParameter;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.handler.invocation.MethodArgumentResolutionException;
 import org.springframework.validation.BindingResult;
@@ -34,8 +35,7 @@ import org.springframework.validation.ObjectError;
 @SuppressWarnings("serial")
 public class MethodArgumentNotValidException extends MethodArgumentResolutionException {
 
-	@Nullable
-	private final BindingResult bindingResult;
+	private final @Nullable BindingResult bindingResult;
 
 
 	/**
@@ -60,8 +60,7 @@ public class MethodArgumentNotValidException extends MethodArgumentResolutionExc
 	 * Return the BindingResult if the failure is validation-related,
 	 * or {@code null} if none.
 	 */
-	@Nullable
-	public final BindingResult getBindingResult() {
+	public final @Nullable BindingResult getBindingResult() {
 		return this.bindingResult;
 	}
 

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/PayloadMethodArgumentResolver.java

@@ -19,8 +19,9 @@ package org.springframework.messaging.handler.annotation.support;
 import java.lang.annotation.Annotation;
 import java.util.Optional;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.MethodParameter;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.converter.MessageConversionException;
 import org.springframework.messaging.converter.MessageConverter;
@@ -61,8 +62,7 @@ public class PayloadMethodArgumentResolver implements HandlerMethodArgumentResol
 
 	private final MessageConverter converter;
 
-	@Nullable
-	private final Validator validator;
+	private final @Nullable Validator validator;
 
 	private final boolean useDefaultResolution;
 
@@ -111,8 +111,7 @@ public class PayloadMethodArgumentResolver implements HandlerMethodArgumentResol
 	}
 
 	@Override
-	@Nullable
-	public Object resolveArgument(MethodParameter parameter, Message<?> message) throws Exception {
+	public @Nullable Object resolveArgument(MethodParameter parameter, Message<?> message) throws Exception {
 		Payload ann = parameter.getParameterAnnotation(Payload.class);
 		if (ann != null && StringUtils.hasText(ann.expression())) {
 			throw new IllegalStateException("@Payload SpEL expressions not supported by this resolver");

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/package-info.java

@@ -1,9 +1,7 @@
 /**
  * Support classes for working with annotated message-handling methods.
  */
-@NonNullApi
-@NonNullFields
+@NullMarked
 package org.springframework.messaging.handler.annotation.support;
 
-import org.springframework.lang.NonNullApi;
-import org.springframework.lang.NonNullFields;
+import org.jspecify.annotations.NullMarked;

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/AbstractAsyncReturnValueHandler.java

@@ -16,8 +16,9 @@
 
 package org.springframework.messaging.handler.invocation;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.MethodParameter;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 
 /**

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/AbstractExceptionHandlerMethodResolver.java

@@ -22,8 +22,9 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.ExceptionDepthComparator;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ConcurrentReferenceHashMap;
 
@@ -98,8 +99,7 @@ public abstract class AbstractExceptionHandlerMethodResolver {
 	 * @param exception the exception
 	 * @return a Method to handle the exception, or {@code null} if none found
 	 */
-	@Nullable
-	public Method resolveMethod(Throwable exception) {
+	public @Nullable Method resolveMethod(Throwable exception) {
 		Method method = resolveMethodByExceptionType(exception.getClass());
 		if (method == null) {
 			Throwable cause = exception.getCause();
@@ -118,8 +118,7 @@ public abstract class AbstractExceptionHandlerMethodResolver {
 	 * @return a Method to handle the exception, or {@code null} if none found
 	 * @since 4.3.1
 	 */
-	@Nullable
-	public Method resolveMethodByExceptionType(Class<? extends Throwable> exceptionType) {
+	public @Nullable Method resolveMethodByExceptionType(Class<? extends Throwable> exceptionType) {
 		Method method = this.exceptionLookupCache.get(exceptionType);
 		if (method == null) {
 			method = getMappedMethod(exceptionType);
@@ -132,8 +131,7 @@ public abstract class AbstractExceptionHandlerMethodResolver {
 	 * Return the {@link Method} mapped to the given exception type, or
 	 * {@link #NO_MATCHING_EXCEPTION_HANDLER_METHOD} if none.
 	 */
-	@Nullable
-	private Method getMappedMethod(Class<? extends Throwable> exceptionType) {
+	private @Nullable Method getMappedMethod(Class<? extends Throwable> exceptionType) {
 		List<Class<? extends Throwable>> matches = new ArrayList<>();
 		for (Class<? extends Throwable> mappedException : this.mappedMethods.keySet()) {
 			if (mappedException.isAssignableFrom(exceptionType)) {

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/AbstractMethodMessageHandler.java

@@ -34,13 +34,13 @@ import java.util.stream.Collectors;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextAware;
 import org.springframework.core.MethodIntrospector;
 import org.springframework.core.MethodParameter;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHandler;
 import org.springframework.messaging.MessageHandlingException;
@@ -89,8 +89,7 @@ public abstract class AbstractMethodMessageHandler<T>
 
 	protected final Log logger = LogFactory.getLog(getClass());
 
-	@Nullable
-	private Log handlerMethodLogger;
+	private @Nullable Log handlerMethodLogger;
 
 
 	private final List<String> destinationPrefixes = new ArrayList<>();
@@ -105,8 +104,7 @@ public abstract class AbstractMethodMessageHandler<T>
 	private final HandlerMethodReturnValueHandlerComposite returnValueHandlers =
 			new HandlerMethodReturnValueHandlerComposite();
 
-	@Nullable
-	private ApplicationContext applicationContext;
+	private @Nullable ApplicationContext applicationContext;
 
 	private final Map<T, HandlerMethod> handlerMethods = new LinkedHashMap<>(64);
 
@@ -225,8 +223,7 @@ public abstract class AbstractMethodMessageHandler<T>
 		this.applicationContext = applicationContext;
 	}
 
-	@Nullable
-	public ApplicationContext getApplicationContext() {
+	public @Nullable ApplicationContext getApplicationContext() {
 		return this.applicationContext;
 	}
 
@@ -343,8 +340,7 @@ public abstract class AbstractMethodMessageHandler<T>
 	 * @param handlerType the handler type, possibly a subtype of the method's declaring class
 	 * @return the mapping, or {@code null} if the method is not mapped
 	 */
-	@Nullable
-	protected abstract T getMappingForMethod(Method method, Class<?> handlerType);
+	protected abstract @Nullable T getMappingForMethod(Method method, Class<?> handlerType);
 
 	/**
 	 * Register a handler method and its unique mapping.
@@ -399,8 +395,7 @@ public abstract class AbstractMethodMessageHandler<T>
 	 * Return a logger to set on {@link HandlerMethodReturnValueHandlerComposite}.
 	 * @since 5.1
 	 */
-	@Nullable
-	protected Log getReturnValueHandlerLogger() {
+	protected @Nullable Log getReturnValueHandlerLogger() {
 		return null;
 	}
 
@@ -408,8 +403,7 @@ public abstract class AbstractMethodMessageHandler<T>
 	 * Return a logger to set on {@link InvocableHandlerMethod}.
 	 * @since 5.1
 	 */
-	@Nullable
-	protected Log getHandlerMethodLogger() {
+	protected @Nullable Log getHandlerMethodLogger() {
 		return null;
 	}
 
@@ -458,8 +452,7 @@ public abstract class AbstractMethodMessageHandler<T>
 		headerAccessor.setImmutable();
 	}
 
-	@Nullable
-	protected abstract String getDestination(Message<?> message);
+	protected abstract @Nullable String getDestination(Message<?> message);
 
 	/**
 	 * Check whether the given destination (of an incoming message) matches to
@@ -469,8 +462,7 @@ public abstract class AbstractMethodMessageHandler<T>
 	 * <p>If there are no destination prefixes, return the destination as is.
 	 */
 	@SuppressWarnings("ForLoopReplaceableByForEach")
-	@Nullable
-	protected String getLookupDestination(@Nullable String destination) {
+	protected @Nullable String getLookupDestination(@Nullable String destination) {
 		if (destination == null) {
 			return null;
 		}
@@ -539,8 +531,7 @@ public abstract class AbstractMethodMessageHandler<T>
 	 * @param message the message being handled
 	 * @return the match or {@code null} if there is no match
 	 */
-	@Nullable
-	protected abstract T getMatchingMapping(T mapping, Message<?> message);
+	protected abstract @Nullable T getMatchingMapping(T mapping, Message<?> message);
 
 	protected void handleNoMatch(Set<T> ts, String lookupDestination, Message<?> message) {
 		logger.debug("No matching message handler methods.");
@@ -628,8 +619,7 @@ public abstract class AbstractMethodMessageHandler<T>
 	 * @return a method to handle the exception, or {@code null}
 	 * @since 4.2
 	 */
-	@Nullable
-	protected InvocableHandlerMethod getExceptionHandlerMethod(HandlerMethod handlerMethod, Exception exception) {
+	protected @Nullable InvocableHandlerMethod getExceptionHandlerMethod(HandlerMethod handlerMethod, Exception exception) {
 		if (logger.isDebugEnabled()) {
 			logger.debug("Searching methods to handle " + exception.getClass().getSimpleName());
 		}

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/AsyncHandlerMethodReturnValueHandler.java

@@ -18,8 +18,9 @@ package org.springframework.messaging.handler.invocation;
 
 import java.util.concurrent.CompletableFuture;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.MethodParameter;
-import org.springframework.lang.Nullable;
 
 /**
  * An extension of {@link HandlerMethodReturnValueHandler} for handling async,
@@ -61,7 +62,6 @@ public interface AsyncHandlerMethodReturnValueHandler extends HandlerMethodRetur
 	 * no further handling will be performed
 	 * @since 6.0
 	 */
-	@Nullable
-	CompletableFuture<?> toCompletableFuture(Object returnValue, MethodParameter returnType);
+	@Nullable CompletableFuture<?> toCompletableFuture(Object returnValue, MethodParameter returnType);
 
 }

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/HandlerMethodArgumentResolver.java

@@ -16,8 +16,9 @@
 
 package org.springframework.messaging.handler.invocation;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.MethodParameter;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 
 /**
@@ -48,7 +49,6 @@ public interface HandlerMethodArgumentResolver {
 	 * @return the resolved argument value, or {@code null}
 	 * @throws Exception in case of errors with the preparation of argument values
 	 */
-	@Nullable
-	Object resolveArgument(MethodParameter parameter, Message<?> message) throws Exception;
+	@Nullable Object resolveArgument(MethodParameter parameter, Message<?> message) throws Exception;
 
 }

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/HandlerMethodArgumentResolverComposite.java

@@ -22,8 +22,9 @@ import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.MethodParameter;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 
 /**
@@ -108,8 +109,7 @@ public class HandlerMethodArgumentResolverComposite implements HandlerMethodArgu
 	 * @throws IllegalArgumentException if no suitable argument resolver is found
 	 */
 	@Override
-	@Nullable
-	public Object resolveArgument(MethodParameter parameter, Message<?> message) throws Exception {
+	public @Nullable Object resolveArgument(MethodParameter parameter, Message<?> message) throws Exception {
 		HandlerMethodArgumentResolver resolver = getArgumentResolver(parameter);
 		if (resolver == null) {
 			throw new IllegalArgumentException("Unsupported parameter type [" +
@@ -122,8 +122,7 @@ public class HandlerMethodArgumentResolverComposite implements HandlerMethodArgu
 	 * Find a registered {@link HandlerMethodArgumentResolver} that supports
 	 * the given method parameter.
 	 */
-	@Nullable
-	private HandlerMethodArgumentResolver getArgumentResolver(MethodParameter parameter) {
+	private @Nullable HandlerMethodArgumentResolver getArgumentResolver(MethodParameter parameter) {
 		HandlerMethodArgumentResolver result = this.argumentResolverCache.get(parameter);
 		if (result == null) {
 			for (HandlerMethodArgumentResolver resolver : this.argumentResolvers) {

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/HandlerMethodReturnValueHandler.java

@@ -16,8 +16,9 @@
 
 package org.springframework.messaging.handler.invocation;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.MethodParameter;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 
 /**

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/HandlerMethodReturnValueHandlerComposite.java

@@ -23,9 +23,9 @@ import java.util.concurrent.CompletableFuture;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.core.MethodParameter;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 
 /**
@@ -102,8 +102,7 @@ public class HandlerMethodReturnValueHandlerComposite implements AsyncHandlerMet
 	}
 
 	@SuppressWarnings("ForLoopReplaceableByForEach")
-	@Nullable
-	private HandlerMethodReturnValueHandler getReturnValueHandler(MethodParameter returnType) {
+	private @Nullable HandlerMethodReturnValueHandler getReturnValueHandler(MethodParameter returnType) {
 		for (HandlerMethodReturnValueHandler handler : this.returnValueHandlers) {
 			if (handler.supportsReturnType(returnType)) {
 				return handler;
@@ -134,8 +133,7 @@ public class HandlerMethodReturnValueHandlerComposite implements AsyncHandlerMet
 	}
 
 	@Override
-	@Nullable
-	public CompletableFuture<?> toCompletableFuture(Object returnValue, MethodParameter returnType) {
+	public @Nullable CompletableFuture<?> toCompletableFuture(Object returnValue, MethodParameter returnType) {
 		HandlerMethodReturnValueHandler handler = getReturnValueHandler(returnType);
 		if (handler instanceof AsyncHandlerMethodReturnValueHandler asyncHandler) {
 			return asyncHandler.toCompletableFuture(returnValue, returnType);

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/InvocableHandlerMethod.java

@@ -21,11 +21,12 @@ import java.lang.reflect.Method;
 import java.lang.reflect.Type;
 import java.util.Arrays;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.DefaultParameterNameDiscoverer;
 import org.springframework.core.MethodParameter;
 import org.springframework.core.ParameterNameDiscoverer;
 import org.springframework.core.ResolvableType;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.handler.HandlerMethod;
 import org.springframework.util.ObjectUtils;
@@ -110,9 +111,8 @@ public class InvocableHandlerMethod extends HandlerMethod {
 	 * @see #getMethodArgumentValues
 	 * @see #doInvoke
 	 */
-	@Nullable
-	public Object invoke(Message<?> message, @Nullable Object... providedArgs) throws Exception {
-		Object[] args = getMethodArgumentValues(message, providedArgs);
+	public @Nullable Object invoke(Message<?> message, @Nullable Object... providedArgs) throws Exception {
+		@Nullable Object[] args = getMethodArgumentValues(message, providedArgs);
 		if (logger.isTraceEnabled()) {
 			logger.trace("Arguments: " + Arrays.toString(args));
 		}
@@ -125,13 +125,13 @@ public class InvocableHandlerMethod extends HandlerMethod {
 	 * <p>The resulting array will be passed into {@link #doInvoke}.
 	 * @since 5.1.2
 	 */
-	protected Object[] getMethodArgumentValues(Message<?> message, @Nullable Object... providedArgs) throws Exception {
+	protected @Nullable Object[] getMethodArgumentValues(Message<?> message, @Nullable Object... providedArgs) throws Exception {
 		MethodParameter[] parameters = getMethodParameters();
 		if (ObjectUtils.isEmpty(parameters)) {
 			return EMPTY_ARGS;
 		}
 
-		Object[] args = new Object[parameters.length];
+		@Nullable Object[] args = new Object[parameters.length];
 		for (int i = 0; i < parameters.length; i++) {
 			MethodParameter parameter = parameters[i];
 			parameter.initParameterNameDiscovery(this.parameterNameDiscoverer);
@@ -163,8 +163,7 @@ public class InvocableHandlerMethod extends HandlerMethod {
 	/**
 	 * Invoke the handler method with the given argument values.
 	 */
-	@Nullable
-	protected Object doInvoke(Object... args) throws Exception {
+	protected @Nullable Object doInvoke(@Nullable Object... args) throws Exception {
 		try {
 			return getBridgedMethod().invoke(getBean(), args);
 		}
@@ -199,8 +198,7 @@ public class InvocableHandlerMethod extends HandlerMethod {
 
 	private class AsyncResultMethodParameter extends AnnotatedMethodParameter {
 
-		@Nullable
-		private final Object returnValue;
+		private final @Nullable Object returnValue;
 
 		private final ResolvableType returnType;
 

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/MethodArgumentResolutionException.java

@@ -16,8 +16,9 @@
 
 package org.springframework.messaging.handler.invocation;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.MethodParameter;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessagingException;
 

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/ReactiveReturnValueHandler.java

@@ -18,12 +18,12 @@ package org.springframework.messaging.handler.invocation;
 
 import java.util.concurrent.CompletableFuture;
 
+import org.jspecify.annotations.Nullable;
 import reactor.core.publisher.Mono;
 
 import org.springframework.core.MethodParameter;
 import org.springframework.core.ReactiveAdapter;
 import org.springframework.core.ReactiveAdapterRegistry;
-import org.springframework.lang.Nullable;
 
 /**
  * Support for single-value reactive types (like {@code Mono} or {@code Single})
@@ -58,8 +58,7 @@ public class ReactiveReturnValueHandler extends AbstractAsyncReturnValueHandler
 	}
 
 	@Override
-	@Nullable
-	public CompletableFuture<?> toCompletableFuture(Object returnValue, MethodParameter returnType) {
+	public @Nullable CompletableFuture<?> toCompletableFuture(Object returnValue, MethodParameter returnType) {
 		ReactiveAdapter adapter = this.adapterRegistry.getAdapter(returnType.getParameterType(), returnValue);
 		if (adapter != null) {
 			return Mono.from(adapter.toPublisher(returnValue)).toFuture();

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/package-info.java

@@ -1,9 +1,7 @@
 /**
  * Common infrastructure for invoking message handler methods.
  */
-@NonNullApi
-@NonNullFields
+@NullMarked
 package org.springframework.messaging.handler.invocation;
 
-import org.springframework.lang.NonNullApi;
-import org.springframework.lang.NonNullFields;
+import org.jspecify.annotations.NullMarked;

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/reactive/AbstractEncoderMethodReturnValueHandler.java

@@ -23,6 +23,7 @@ import java.util.Map;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
@@ -36,7 +37,6 @@ import org.springframework.core.codec.Encoder;
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DataBufferFactory;
 import org.springframework.core.io.buffer.DefaultDataBufferFactory;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHeaders;
 import org.springframework.messaging.MessagingException;
@@ -166,9 +166,8 @@ public abstract class AbstractEncoderMethodReturnValueHandler implements Handler
 		}
 	}
 
-	@Nullable
 	@SuppressWarnings("unchecked")
-	private <T> Encoder<T> getEncoder(ResolvableType elementType, @Nullable MimeType mimeType) {
+	private <T> @Nullable Encoder<T> getEncoder(ResolvableType elementType, @Nullable MimeType mimeType) {
 		for (Encoder<?> encoder : getEncoders()) {
 			if (encoder.canEncode(elementType, mimeType)) {
 				return (Encoder<T>) encoder;

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/reactive/AbstractMethodMessageHandler.java

@@ -33,6 +33,7 @@ import java.util.stream.Collectors;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 import reactor.core.publisher.Mono;
 
 import org.springframework.beans.factory.BeanNameAware;
@@ -41,7 +42,6 @@ import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextAware;
 import org.springframework.core.MethodIntrospector;
 import org.springframework.core.ReactiveAdapterRegistry;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessagingException;
 import org.springframework.messaging.ReactiveMessageHandler;
@@ -87,11 +87,9 @@ public abstract class AbstractMethodMessageHandler<T>
 	protected final Log logger = LogFactory.getLog(getClass());
 
 
-	@Nullable
-	private Predicate<Class<?>> handlerPredicate;
+	private @Nullable Predicate<Class<?>> handlerPredicate;
 
-	@Nullable
-	List<Object> handlers;
+	@Nullable List<Object> handlers;
 
 	private ArgumentResolverConfigurer argumentResolverConfigurer = new ArgumentResolverConfigurer();
 
@@ -99,11 +97,9 @@ public abstract class AbstractMethodMessageHandler<T>
 
 	private final InvocableHelper invocableHelper = new InvocableHelper(this::createExceptionMethodResolverFor);
 
-	@Nullable
-	private ApplicationContext applicationContext;
+	private @Nullable ApplicationContext applicationContext;
 
-	@Nullable
-	private String beanName;
+	private @Nullable String beanName;
 
 	private final Map<T, HandlerMethod> handlerMethods = new ConcurrentHashMap<>(64);
 
@@ -124,8 +120,7 @@ public abstract class AbstractMethodMessageHandler<T>
 	/**
 	 * Return the {@link #setHandlerPredicate configured} handler predicate.
 	 */
-	@Nullable
-	public Predicate<Class<?>> getHandlerPredicate() {
+	public @Nullable Predicate<Class<?>> getHandlerPredicate() {
 		return this.handlerPredicate;
 	}
 
@@ -193,8 +188,7 @@ public abstract class AbstractMethodMessageHandler<T>
 		this.applicationContext = applicationContext;
 	}
 
-	@Nullable
-	public ApplicationContext getApplicationContext() {
+	public @Nullable ApplicationContext getApplicationContext() {
 		return this.applicationContext;
 	}
 
@@ -365,8 +359,7 @@ public abstract class AbstractMethodMessageHandler<T>
 	 * @param handlerType the handler type, possibly a subtype of the method's declaring class
 	 * @return the mapping, or {@code null} if the method is not mapped
 	 */
-	@Nullable
-	protected abstract T getMappingForMethod(Method method, Class<?> handlerType);
+	protected abstract @Nullable T getMappingForMethod(Method method, Class<?> handlerType);
 
 	/**
 	 * Register a handler method and its unique mapping.
@@ -461,8 +454,7 @@ public abstract class AbstractMethodMessageHandler<T>
 		return this.invocableHelper.handleMessage(handlerMethod, message);
 	}
 
-	@Nullable
-	private Match<T> getHandlerMethod(Message<?> message) {
+	private @Nullable Match<T> getHandlerMethod(Message<?> message) {
 		List<Match<T>> matches = new ArrayList<>();
 
 		RouteMatcher.Route destination = getDestination(message);
@@ -502,8 +494,7 @@ public abstract class AbstractMethodMessageHandler<T>
 	 * Extract the destination from the given message.
 	 * @see #getDirectLookupMappings(Object)
 	 */
-	@Nullable
-	protected abstract RouteMatcher.Route getDestination(Message<?> message);
+	protected abstract RouteMatcher.@Nullable Route getDestination(Message<?> message);
 
 	@SuppressWarnings("NullAway")
 	private void addMatchesToCollection(
@@ -524,8 +515,7 @@ public abstract class AbstractMethodMessageHandler<T>
 	 * @param message the message being handled
 	 * @return the match or {@code null} if there is no match
 	 */
-	@Nullable
-	protected abstract T getMatchingMapping(T mapping, Message<?> message);
+	protected abstract @Nullable T getMatchingMapping(T mapping, Message<?> message);
 
 	/**
 	 * Return a comparator for sorting matching mappings.
@@ -540,7 +530,7 @@ public abstract class AbstractMethodMessageHandler<T>
 	 * @param destination the destination
 	 * @param message the message
 	 */
-	protected void handleNoMatch(@Nullable RouteMatcher.Route destination, Message<?> message) {
+	protected void handleNoMatch(RouteMatcher.@Nullable Route destination, Message<?> message) {
 		logger.debug("No handlers for destination '" +
 				(destination != null ? destination.value() : "") + "'");
 	}

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/reactive/ChannelSendOperator.java

@@ -18,6 +18,7 @@ package org.springframework.messaging.handler.invocation.reactive;
 
 import java.util.function.Function;
 
+import org.jspecify.annotations.Nullable;
 import org.reactivestreams.Publisher;
 import org.reactivestreams.Subscriber;
 import org.reactivestreams.Subscription;
@@ -30,7 +31,6 @@ import reactor.util.context.Context;
 
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DataBufferUtils;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -68,9 +68,8 @@ class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 
 
 	@Override
-	@Nullable
 	@SuppressWarnings("rawtypes")
-	public Object scanUnsafe(Attr key) {
+	public @Nullable Object scanUnsafe(Attr key) {
 		if (key == Attr.PREFETCH) {
 			return Integer.MAX_VALUE;
 		}
@@ -134,16 +133,13 @@ class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 		private final WriteCompletionBarrier writeCompletionBarrier;
 
 		/* Upstream write source subscription */
-		@Nullable
-		private Subscription subscription;
+		private @Nullable Subscription subscription;
 
 		/** Cached data item before readyToWrite. */
-		@Nullable
-		private T item;
+		private @Nullable T item;
 
 		/** Cached error signal before readyToWrite. */
-		@Nullable
-		private Throwable error;
+		private @Nullable Throwable error;
 
 		/** Cached onComplete signal before readyToWrite. */
 		private boolean completed = false;
@@ -155,8 +151,7 @@ class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 		private State state = State.NEW;
 
 		/** The actual writeSubscriber from the HTTP server adapter. */
-		@Nullable
-		private Subscriber<? super T> writeSubscriber;
+		private @Nullable Subscriber<? super T> writeSubscriber;
 
 
 		WriteBarrier(CoreSubscriber<? super Void> completionSubscriber) {
@@ -391,8 +386,7 @@ class ChannelSendOperator<T> extends Mono<Void> implements Scannable {
 
 		private final WriteBarrier writeBarrier;
 
-		@Nullable
-		private Subscription subscription;
+		private @Nullable Subscription subscription;
 
 
 		public WriteCompletionBarrier(CoreSubscriber<? super Void> subscriber, WriteBarrier writeBarrier) {

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/reactive/HandlerMethodArgumentResolverComposite.java

@@ -24,10 +24,10 @@ import java.util.concurrent.ConcurrentHashMap;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 import reactor.core.publisher.Mono;
 
 import org.springframework.core.MethodParameter;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 
 /**
@@ -124,8 +124,7 @@ public class HandlerMethodArgumentResolverComposite implements HandlerMethodArgu
 	 * Find a registered {@link HandlerMethodArgumentResolver} that supports
 	 * the given method parameter.
 	 */
-	@Nullable
-	public HandlerMethodArgumentResolver getArgumentResolver(MethodParameter parameter) {
+	public @Nullable HandlerMethodArgumentResolver getArgumentResolver(MethodParameter parameter) {
 		HandlerMethodArgumentResolver result = this.argumentResolverCache.get(parameter);
 		if (result == null) {
 			for (HandlerMethodArgumentResolver methodArgumentResolver : this.argumentResolvers) {

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/reactive/HandlerMethodReturnValueHandler.java

@@ -16,10 +16,10 @@
 
 package org.springframework.messaging.handler.invocation.reactive;
 
+import org.jspecify.annotations.Nullable;
 import reactor.core.publisher.Mono;
 
 import org.springframework.core.MethodParameter;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 
 /**

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/reactive/HandlerMethodReturnValueHandlerComposite.java

@@ -22,10 +22,10 @@ import java.util.List;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 import reactor.core.publisher.Mono;
 
 import org.springframework.core.MethodParameter;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 
 /**
@@ -93,8 +93,7 @@ public class HandlerMethodReturnValueHandlerComposite implements HandlerMethodRe
 	}
 
 	@SuppressWarnings("ForLoopReplaceableByForEach")
-	@Nullable
-	private HandlerMethodReturnValueHandler getReturnValueHandler(MethodParameter returnType) {
+	private @Nullable HandlerMethodReturnValueHandler getReturnValueHandler(MethodParameter returnType) {
 		for (HandlerMethodReturnValueHandler handler : this.returnValueHandlers) {
 			if (handler.supportsReturnType(returnType)) {
 				return handler;

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/reactive/InvocableHelper.java

@@ -25,11 +25,11 @@ import java.util.function.Function;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 import reactor.core.publisher.Mono;
 
 import org.springframework.core.MethodParameter;
 import org.springframework.core.ReactiveAdapterRegistry;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.handler.HandlerMethod;
 import org.springframework.messaging.handler.MessagingAdviceBean;
@@ -146,8 +146,7 @@ class InvocableHelper {
 	 * @param ex the exception raised or signaled
 	 * @return a method to handle the exception, or {@code null}
 	 */
-	@Nullable
-	public InvocableHandlerMethod initExceptionHandlerMethod(HandlerMethod handlerMethod, Throwable ex) {
+	public @Nullable InvocableHandlerMethod initExceptionHandlerMethod(HandlerMethod handlerMethod, Throwable ex) {
 		if (logger.isDebugEnabled()) {
 			logger.debug("Searching for methods to handle " + ex.getClass().getSimpleName());
 		}

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/reactive/SyncHandlerMethodArgumentResolver.java

@@ -16,10 +16,10 @@
 
 package org.springframework.messaging.handler.invocation.reactive;
 
+import org.jspecify.annotations.Nullable;
 import reactor.core.publisher.Mono;
 
 import org.springframework.core.MethodParameter;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 
 /**
@@ -47,7 +47,6 @@ public interface SyncHandlerMethodArgumentResolver extends HandlerMethodArgument
 	 * @param message the currently processed message
 	 * @return the resolved value, if any
 	 */
-	@Nullable
-	Object resolveArgumentValue(MethodParameter parameter, Message<?> message);
+	@Nullable Object resolveArgumentValue(MethodParameter parameter, Message<?> message);
 
 }

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/reactive/package-info.java

@@ -2,9 +2,7 @@
  * Common infrastructure for invoking message handler methods with non-blocking,
  * and reactive contracts.
  */
-@NonNullApi
-@NonNullFields
+@NullMarked
 package org.springframework.messaging.handler.invocation.reactive;
 
-import org.springframework.lang.NonNullApi;
-import org.springframework.lang.NonNullFields;
+import org.jspecify.annotations.NullMarked;

spring-messaging/src/main/java/org/springframework/messaging/handler/package-info.java

@@ -1,9 +1,7 @@
 /**
  * Basic abstractions for working with message handler methods.
  */
-@NonNullApi
-@NonNullFields
+@NullMarked
 package org.springframework.messaging.handler;
 
-import org.springframework.lang.NonNullApi;
-import org.springframework.lang.NonNullFields;
+import org.jspecify.annotations.NullMarked;

spring-messaging/src/main/java/org/springframework/messaging/package-info.java

@@ -1,9 +1,7 @@
 /**
  * Support for working with messaging APIs and protocols.
  */
-@NonNullApi
-@NonNullFields
+@NullMarked
 package org.springframework.messaging;
 
-import org.springframework.lang.NonNullApi;
-import org.springframework.lang.NonNullFields;
+import org.jspecify.annotations.NullMarked;

spring-messaging/src/main/java/org/springframework/messaging/rsocket/DefaultMetadataExtractor.java

@@ -32,13 +32,13 @@ import io.rsocket.metadata.RoutingMetadata;
 import io.rsocket.metadata.WellKnownMimeType;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.core.ResolvableType;
 import org.springframework.core.codec.Decoder;
 import org.springframework.core.io.buffer.NettyDataBuffer;
 import org.springframework.core.io.buffer.NettyDataBufferFactory;
-import org.springframework.lang.Nullable;
 import org.springframework.util.MimeType;
 
 /**

spring-messaging/src/main/java/org/springframework/messaging/rsocket/DefaultRSocketRequester.java

@@ -23,6 +23,7 @@ import java.util.function.Consumer;
 import io.rsocket.Payload;
 import io.rsocket.RSocket;
 import io.rsocket.core.RSocketClient;
+import org.jspecify.annotations.Nullable;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
@@ -35,7 +36,6 @@ import org.springframework.core.codec.Encoder;
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DataBufferFactory;
 import org.springframework.core.io.buffer.DataBufferUtils;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.MimeType;
@@ -52,8 +52,7 @@ final class DefaultRSocketRequester implements RSocketRequester {
 
 	private final RSocketClient rsocketClient;
 
-	@Nullable
-	private final RSocket rsocket;
+	private final @Nullable RSocket rsocket;
 
 	private final MimeType dataMimeType;
 
@@ -87,9 +86,8 @@ final class DefaultRSocketRequester implements RSocketRequester {
 		return this.rsocketClient;
 	}
 
-	@Nullable
 	@Override
-	public RSocket rsocket() {
+	public @Nullable RSocket rsocket() {
 		return this.rsocket;
 	}
 
@@ -132,11 +130,9 @@ final class DefaultRSocketRequester implements RSocketRequester {
 
 		private final MetadataEncoder metadataEncoder = new MetadataEncoder(metadataMimeType(), strategies);
 
-		@Nullable
-		private Mono<Payload> payloadMono;
+		private @Nullable Mono<Payload> payloadMono;
 
-		@Nullable
-		private Flux<Payload> payloadFlux;
+		private @Nullable Flux<Payload> payloadFlux;
 
 
 		public DefaultRequestSpec(String route, Object... vars) {
@@ -178,8 +174,7 @@ final class DefaultRSocketRequester implements RSocketRequester {
 			return this;
 		}
 
-		@Nullable
-		private ReactiveAdapter getAdapter(Class<?> aClass) {
+		private @Nullable ReactiveAdapter getAdapter(Class<?> aClass) {
 			return strategies.reactiveAdapterRegistry().getAdapter(aClass);
 		}
 

spring-messaging/src/main/java/org/springframework/messaging/rsocket/DefaultRSocketRequesterBuilder.java

@@ -36,6 +36,7 @@ import io.rsocket.transport.ClientTransport;
 import io.rsocket.transport.netty.client.TcpClientTransport;
 import io.rsocket.transport.netty.client.WebsocketClientTransport;
 import io.rsocket.util.DefaultPayload;
+import org.jspecify.annotations.Nullable;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Mono;
 
@@ -47,7 +48,6 @@ import org.springframework.core.codec.StringDecoder;
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DataBufferUtils;
 import org.springframework.core.io.buffer.NettyDataBufferFactory;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.MimeType;
@@ -69,26 +69,19 @@ final class DefaultRSocketRequesterBuilder implements RSocketRequester.Builder {
 	private static final Payload EMPTY_SETUP_PAYLOAD = DefaultPayload.create(EMPTY_BYTE_ARRAY);
 
 
-	@Nullable
-	private MimeType dataMimeType;
+	private @Nullable MimeType dataMimeType;
 
-	@Nullable
-	private MimeType metadataMimeType;
+	private @Nullable MimeType metadataMimeType;
 
-	@Nullable
-	private Object setupData;
+	private @Nullable Object setupData;
 
-	@Nullable
-	private String setupRoute;
+	private @Nullable String setupRoute;
 
-	@Nullable
-	private Object[] setupRouteVars;
+	private Object @Nullable [] setupRouteVars;
 
-	@Nullable
-	private Map<Object, MimeType> setupMetadata;
+	private @Nullable Map<Object, MimeType> setupMetadata;
 
-	@Nullable
-	private RSocketStrategies strategies;
+	private @Nullable RSocketStrategies strategies;
 
 	private final List<Consumer<RSocketStrategies.Builder>> strategiesConfigurers = new ArrayList<>();
 

spring-messaging/src/main/java/org/springframework/messaging/rsocket/DefaultRSocketStrategies.java

@@ -23,6 +23,7 @@ import java.util.List;
 import java.util.function.Consumer;
 
 import io.netty.buffer.PooledByteBufAllocator;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.core.ReactiveAdapterRegistry;
 import org.springframework.core.codec.ByteArrayDecoder;
@@ -37,7 +38,6 @@ import org.springframework.core.codec.Encoder;
 import org.springframework.core.codec.StringDecoder;
 import org.springframework.core.io.buffer.DataBufferFactory;
 import org.springframework.core.io.buffer.NettyDataBufferFactory;
-import org.springframework.lang.Nullable;
 import org.springframework.util.AntPathMatcher;
 import org.springframework.util.RouteMatcher;
 import org.springframework.util.SimpleRouteMatcher;
@@ -117,17 +117,13 @@ final class DefaultRSocketStrategies implements RSocketStrategies {
 
 		private final List<Decoder<?>> decoders = new ArrayList<>();
 
-		@Nullable
-		private RouteMatcher routeMatcher;
+		private @Nullable RouteMatcher routeMatcher;
 
-		@Nullable
-		private ReactiveAdapterRegistry adapterRegistry = ReactiveAdapterRegistry.getSharedInstance();
+		private @Nullable ReactiveAdapterRegistry adapterRegistry = ReactiveAdapterRegistry.getSharedInstance();
 
-		@Nullable
-		private DataBufferFactory bufferFactory;
+		private @Nullable DataBufferFactory bufferFactory;
 
-		@Nullable
-		private MetadataExtractor metadataExtractor;
+		private @Nullable MetadataExtractor metadataExtractor;
 
 		private final List<Consumer<MetadataExtractorRegistry>> metadataExtractors = new ArrayList<>();
 

spring-messaging/src/main/java/org/springframework/messaging/rsocket/MetadataEncoder.java

@@ -27,6 +27,7 @@ import io.netty.buffer.ByteBuf;
 import io.netty.buffer.ByteBufAllocator;
 import io.netty.buffer.CompositeByteBuf;
 import io.rsocket.metadata.WellKnownMimeType;
+import org.jspecify.annotations.Nullable;
 import reactor.core.publisher.Mono;
 
 import org.springframework.core.ReactiveAdapter;
@@ -35,7 +36,6 @@ import org.springframework.core.codec.Encoder;
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DataBufferFactory;
 import org.springframework.core.io.buffer.NettyDataBufferFactory;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.MimeType;
@@ -63,8 +63,7 @@ final class MetadataEncoder {
 
 	private final ByteBufAllocator allocator;
 
-	@Nullable
-	private String route;
+	private @Nullable String route;
 
 	private final List<MetadataEntry> metadataEntries = new ArrayList<>(4);
 
@@ -155,7 +154,7 @@ final class MetadataEncoder {
 	 * Add route and/or metadata, both optional.
 	 */
 	public MetadataEncoder metadataAndOrRoute(@Nullable Map<Object, MimeType> metadata,
-			@Nullable String route, @Nullable Object[] vars) {
+			@Nullable String route, Object @Nullable [] vars) {
 
 		if (route != null) {
 			this.route = expand(route, vars != null ? vars : new Object[0]);

spring-messaging/src/main/java/org/springframework/messaging/rsocket/MetadataExtractorRegistry.java

@@ -19,8 +19,9 @@ package org.springframework.messaging.rsocket;
 import java.util.Map;
 import java.util.function.BiConsumer;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.ParameterizedTypeReference;
-import org.springframework.lang.Nullable;
 import org.springframework.util.MimeType;
 
 /**

spring-messaging/src/main/java/org/springframework/messaging/rsocket/RSocketRequester.java

@@ -29,6 +29,7 @@ import io.rsocket.loadbalance.LoadbalanceTarget;
 import io.rsocket.transport.ClientTransport;
 import io.rsocket.transport.netty.client.TcpClientTransport;
 import io.rsocket.transport.netty.client.WebsocketClientTransport;
+import org.jspecify.annotations.Nullable;
 import org.reactivestreams.Publisher;
 import reactor.core.Disposable;
 import reactor.core.publisher.Flux;
@@ -37,7 +38,6 @@ import reactor.core.publisher.Mono;
 import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.core.ReactiveAdapterRegistry;
 import org.springframework.core.codec.Decoder;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.rsocket.annotation.support.RSocketMessageHandler;
 import org.springframework.util.MimeType;
 
@@ -64,8 +64,7 @@ public interface RSocketRequester extends Disposable {
 	 * or via one of the (deprecated) connect methods on the
 	 * {@code RSocketRequester} builder, or otherwise return {@code null}.
 	 */
-	@Nullable
-	RSocket rsocket();
+	@Nullable RSocket rsocket();
 
 	/**
 	 * Return the data {@code MimeType} selected for the underlying RSocket

spring-messaging/src/main/java/org/springframework/messaging/rsocket/RSocketStrategies.java

@@ -20,6 +20,7 @@ import java.util.List;
 import java.util.function.Consumer;
 
 import io.rsocket.Payload;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.core.ReactiveAdapterRegistry;
 import org.springframework.core.ResolvableType;
@@ -28,7 +29,6 @@ import org.springframework.core.codec.Encoder;
 import org.springframework.core.io.buffer.DataBufferFactory;
 import org.springframework.core.io.buffer.DefaultDataBufferFactory;
 import org.springframework.core.io.buffer.NettyDataBufferFactory;
-import org.springframework.lang.Nullable;
 import org.springframework.util.AntPathMatcher;
 import org.springframework.util.MimeType;
 import org.springframework.util.RouteMatcher;

spring-messaging/src/main/java/org/springframework/messaging/rsocket/annotation/package-info.java

@@ -1,9 +1,7 @@
 /**
  * Annotations and support classes for handling RSocket streams.
  */
-@NonNullApi
-@NonNullFields
+@NullMarked
 package org.springframework.messaging.rsocket.annotation;
 
-import org.springframework.lang.NonNullApi;
-import org.springframework.lang.NonNullFields;
+import org.jspecify.annotations.NullMarked;

spring-messaging/src/main/java/org/springframework/messaging/rsocket/annotation/support/MessagingRSocket.java

@@ -24,6 +24,7 @@ import io.rsocket.ConnectionSetupPayload;
 import io.rsocket.Payload;
 import io.rsocket.RSocket;
 import io.rsocket.frame.FrameType;
+import org.jspecify.annotations.Nullable;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
@@ -31,7 +32,6 @@ import reactor.core.publisher.Mono;
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DataBufferUtils;
 import org.springframework.core.io.buffer.NettyDataBuffer;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHeaders;
 import org.springframework.messaging.ReactiveMessageHandler;

spring-messaging/src/main/java/org/springframework/messaging/rsocket/annotation/support/RSocketFrameTypeMessageCondition.java

@@ -24,8 +24,8 @@ import java.util.Map;
 import java.util.Set;
 
 import io.rsocket.frame.FrameType;
+import org.jspecify.annotations.Nullable;
 
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.handler.AbstractMessageCondition;
 import org.springframework.util.Assert;
@@ -117,8 +117,7 @@ public class RSocketFrameTypeMessageCondition extends AbstractMessageCondition<R
 	 * @param message the current message
 	 * @return the frame type or {@code null} if not found
 	 */
-	@Nullable
-	public static FrameType getFrameType(Message<?> message) {
+	public static @Nullable FrameType getFrameType(Message<?> message) {
 		return (FrameType) message.getHeaders().get(RSocketFrameTypeMessageCondition.FRAME_TYPE_HEADER);
 	}
 
@@ -134,8 +133,7 @@ public class RSocketFrameTypeMessageCondition extends AbstractMessageCondition<R
 	}
 
 	@Override
-	@Nullable
-	public RSocketFrameTypeMessageCondition getMatchingCondition(Message<?> message) {
+	public @Nullable RSocketFrameTypeMessageCondition getMatchingCondition(Message<?> message) {
 		FrameType actual = message.getHeaders().get(FRAME_TYPE_HEADER, FrameType.class);
 		if (actual != null) {
 			for (FrameType type : this.frameTypes) {

spring-messaging/src/main/java/org/springframework/messaging/rsocket/annotation/support/RSocketMessageHandler.java

@@ -28,6 +28,7 @@ import io.rsocket.RSocket;
 import io.rsocket.SocketAcceptor;
 import io.rsocket.frame.FrameType;
 import io.rsocket.metadata.WellKnownMimeType;
+import org.jspecify.annotations.Nullable;
 import reactor.core.publisher.Mono;
 
 import org.springframework.beans.BeanUtils;
@@ -38,7 +39,6 @@ import org.springframework.core.annotation.AnnotatedElementUtils;
 import org.springframework.core.codec.Decoder;
 import org.springframework.core.codec.Encoder;
 import org.springframework.core.io.buffer.PooledDataBuffer;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageDeliveryException;
 import org.springframework.messaging.handler.CompositeMessageCondition;
@@ -96,8 +96,7 @@ public class RSocketMessageHandler extends MessageMappingMessageHandler {
 
 	private RSocketStrategies strategies = RSocketStrategies.create();
 
-	@Nullable
-	private MimeType defaultDataMimeType;
+	private @Nullable MimeType defaultDataMimeType;
 
 	private MimeType defaultMetadataMimeType = MimeTypeUtils.parseMimeType(
 			WellKnownMimeType.MESSAGE_RSOCKET_COMPOSITE_METADATA.getString());
@@ -256,8 +255,7 @@ public class RSocketMessageHandler extends MessageMappingMessageHandler {
 	 * Return the configured
 	 * {@link #setDefaultDataMimeType defaultDataMimeType}, or {@code null}.
 	 */
-	@Nullable
-	public MimeType getDefaultDataMimeType() {
+	public @Nullable MimeType getDefaultDataMimeType() {
 		return this.defaultDataMimeType;
 	}
 
@@ -311,8 +309,7 @@ public class RSocketMessageHandler extends MessageMappingMessageHandler {
 
 
 	@Override
-	@Nullable
-	protected CompositeMessageCondition getCondition(AnnotatedElement element) {
+	protected @Nullable CompositeMessageCondition getCondition(AnnotatedElement element) {
 		MessageMapping ann1 = AnnotatedElementUtils.findMergedAnnotation(element, MessageMapping.class);
 		if (ann1 != null && ann1.value().length > 0) {
 			return new CompositeMessageCondition(
@@ -379,7 +376,7 @@ public class RSocketMessageHandler extends MessageMappingMessageHandler {
 	}
 
 	@Override
-	protected void handleNoMatch(@Nullable RouteMatcher.Route destination, Message<?> message) {
+	protected void handleNoMatch(RouteMatcher.@Nullable Route destination, Message<?> message) {
 		FrameType frameType = RSocketFrameTypeMessageCondition.getFrameType(message);
 		if (frameType == FrameType.SETUP || frameType == FrameType.METADATA_PUSH) {
 			if (frameType == FrameType.SETUP && message.getPayload() instanceof PooledDataBuffer pooledDataBuffer) {

spring-messaging/src/main/java/org/springframework/messaging/rsocket/annotation/support/RSocketPayloadReturnValueHandler.java

@@ -20,6 +20,7 @@ import java.util.List;
 import java.util.concurrent.atomic.AtomicReference;
 
 import io.rsocket.Payload;
+import org.jspecify.annotations.Nullable;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
@@ -27,7 +28,6 @@ import org.springframework.core.MethodParameter;
 import org.springframework.core.ReactiveAdapterRegistry;
 import org.springframework.core.codec.Encoder;
 import org.springframework.core.io.buffer.DataBuffer;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.handler.invocation.reactive.AbstractEncoderMethodReturnValueHandler;
 import org.springframework.messaging.rsocket.PayloadUtils;
@@ -75,9 +75,8 @@ public class RSocketPayloadReturnValueHandler extends AbstractEncoderMethodRetur
 		return Mono.empty();
 	}
 
-	@Nullable
 	@SuppressWarnings("unchecked")
-	private AtomicReference<Flux<Payload>> getResponseReference(Message<?> message) {
+	private @Nullable AtomicReference<Flux<Payload>> getResponseReference(Message<?> message) {
 		Object headerValue = message.getHeaders().get(RESPONSE_HEADER);
 		Assert.state(headerValue == null || headerValue instanceof AtomicReference, "Expected AtomicReference");
 		return (AtomicReference<Flux<Payload>>) headerValue;

spring-messaging/src/main/java/org/springframework/messaging/rsocket/annotation/support/package-info.java

@@ -1,9 +1,7 @@
 /**
  * Support classes for working with annotated RSocket stream handling methods.
  */
-@NonNullApi
-@NonNullFields
+@NullMarked
 package org.springframework.messaging.rsocket.annotation.support;
 
-import org.springframework.lang.NonNullApi;
-import org.springframework.lang.NonNullFields;
+import org.jspecify.annotations.NullMarked;

spring-messaging/src/main/java/org/springframework/messaging/rsocket/package-info.java

@@ -1,9 +1,7 @@
 /**
  * Support for the RSocket protocol.
  */
-@NonNullApi
-@NonNullFields
+@NullMarked
 package org.springframework.messaging.rsocket;
 
-import org.springframework.lang.NonNullApi;
-import org.springframework.lang.NonNullFields;
+import org.jspecify.annotations.NullMarked;

spring-messaging/src/main/java/org/springframework/messaging/rsocket/service/DestinationVariableArgumentResolver.java

@@ -18,8 +18,9 @@ package org.springframework.messaging.rsocket.service;
 
 import java.util.Collection;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.MethodParameter;
-import org.springframework.lang.Nullable;
 import org.springframework.messaging.handler.annotation.DestinationVariable;
 
 /**

spring-messaging/src/main/java/org/springframework/messaging/rsocket/service/MetadataArgumentResolver.java

@@ -16,8 +16,9 @@
 
 package org.springframework.messaging.rsocket.service;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.MethodParameter;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.MimeType;