Nullability fine-tuning around declaration inconsistencies

Issue: SPR-15720
Issue: SPR-15792

spring-jms/src/main/java/org/springframework/jms/listener/AbstractMessageListenerContainer.java

@@ -31,7 +31,6 @@ import org.springframework.jms.support.JmsUtils;
 import org.springframework.jms.support.QosSettings;
 import org.springframework.jms.support.converter.MessageConverter;
 import org.springframework.lang.Nullable;
-import org.springframework.util.Assert;
 import org.springframework.util.ErrorHandler;
 
 /**
@@ -506,6 +505,7 @@ public abstract class AbstractMessageListenerContainer extends AbstractJmsListen
 	}
 
 	@Override
+	@Nullable
 	public QosSettings getReplyQosSettings() {
 		return this.replyQosSettings;
 	}
@@ -514,11 +514,12 @@ public abstract class AbstractMessageListenerContainer extends AbstractJmsListen
 	 * Set the {@link MessageConverter} strategy for converting JMS Messages.
 	 * @since 4.1
 	 */
-	public void setMessageConverter(MessageConverter messageConverter) {
+	public void setMessageConverter(@Nullable MessageConverter messageConverter) {
 		this.messageConverter = messageConverter;
 	}
 
 	@Override
+	@Nullable
 	public MessageConverter getMessageConverter() {
 		return this.messageConverter;
 	}

spring-jms/src/main/java/org/springframework/jms/listener/adapter/MessageListenerAdapter.java

@@ -144,7 +144,8 @@ public class MessageListenerAdapter extends AbstractAdaptableMessageListener imp
 	 * @param delegate the delegate object
 	 */
 	public MessageListenerAdapter(Object delegate) {
-		setDelegate(delegate);
+		Assert.notNull(delegate, "Delegate must not be null");
+		this.delegate = delegate;
 	}
 
 
@@ -196,12 +197,13 @@ public class MessageListenerAdapter extends AbstractAdaptableMessageListener imp
 	 */
 	@Override
 	@SuppressWarnings("unchecked")
-	public void onMessage(Message message, Session session) throws JMSException {
+	public void onMessage(Message message, @Nullable Session session) throws JMSException {
 		// Check whether the delegate is a MessageListener impl itself.
 		// In that case, the adapter will simply act as a pass-through.
 		Object delegate = getDelegate();
 		if (delegate != this) {
 			if (delegate instanceof SessionAwareMessageListener) {
+				Assert.state(session != null, "Session is required for SessionAwareMessageListener");
 				((SessionAwareMessageListener<Message>) delegate).onMessage(message, session);
 				return;
 			}

spring-jms/src/main/java/org/springframework/jms/listener/adapter/MessagingMessageListenerAdapter.java

@@ -28,6 +28,7 @@ import org.springframework.messaging.MessagingException;
 import org.springframework.messaging.core.AbstractMessageSendingTemplate;
 import org.springframework.messaging.handler.invocation.InvocableHandlerMethod;
 import org.springframework.messaging.support.MessageBuilder;
+import org.springframework.util.Assert;
 
 /**
  * A {@link javax.jms.MessageListener} adapter that invokes a configurable
@@ -49,6 +50,7 @@ import org.springframework.messaging.support.MessageBuilder;
  */
 public class MessagingMessageListenerAdapter extends AbstractAdaptableMessageListener {
 
+	@Nullable
 	private InvocableHandlerMethod handlerMethod;
 
 
@@ -60,9 +62,14 @@ public class MessagingMessageListenerAdapter extends AbstractAdaptableMessageLis
 		this.handlerMethod = handlerMethod;
 	}
 
+	private InvocableHandlerMethod getHandlerMethod() {
+		Assert.state(this.handlerMethod != null, "No HandlerMethod set");
+		return this.handlerMethod;
+	}
+
 
 	@Override
-	public void onMessage(javax.jms.Message jmsMessage, Session session) throws JMSException {
+	public void onMessage(javax.jms.Message jmsMessage, @Nullable Session session) throws JMSException {
 		Message<?> message = toMessagingMessage(jmsMessage);
 		if (logger.isDebugEnabled()) {
 			logger.debug("Processing [" + message + "]");
@@ -78,7 +85,7 @@ public class MessagingMessageListenerAdapter extends AbstractAdaptableMessageLis
 
 	@Override
 	protected Object preProcessResponse(Object result) {
-		MethodParameter returnType = this.handlerMethod.getReturnType();
+		MethodParameter returnType = getHandlerMethod().getReturnType();
 		if (result instanceof Message) {
 			return MessageBuilder.fromMessage((Message<?>) result)
 					.setHeader(AbstractMessageSendingTemplate.CONVERSION_HINT_HEADER, returnType).build();
@@ -101,9 +108,10 @@ public class MessagingMessageListenerAdapter extends AbstractAdaptableMessageLis
 	 * with a dedicated error message.
 	 */
 	@Nullable
-	private Object invokeHandler(javax.jms.Message jmsMessage, Session session, Message<?> message) {
+	private Object invokeHandler(javax.jms.Message jmsMessage, @Nullable Session session, Message<?> message) {
+		InvocableHandlerMethod handlerMethod = getHandlerMethod();
 		try {
-			return this.handlerMethod.invoke(message, jmsMessage, session);
+			return handlerMethod.invoke(message, jmsMessage, session);
 		}
 		catch (MessagingException ex) {
 			throw new ListenerExecutionFailedException(
@@ -111,15 +119,16 @@ public class MessagingMessageListenerAdapter extends AbstractAdaptableMessageLis
 		}
 		catch (Exception ex) {
 			throw new ListenerExecutionFailedException("Listener method '" +
-					this.handlerMethod.getMethod().toGenericString() + "' threw exception", ex);
+					handlerMethod.getMethod().toGenericString() + "' threw exception", ex);
 		}
 	}
 
 	private String createMessagingErrorMessage(String description) {
+		InvocableHandlerMethod handlerMethod = getHandlerMethod();
 		StringBuilder sb = new StringBuilder(description).append("\n")
 				.append("Endpoint handler details:\n")
-				.append("Method [").append(this.handlerMethod.getMethod()).append("]\n")
-				.append("Bean [").append(this.handlerMethod.getBean()).append("]\n");
+				.append("Method [").append(handlerMethod.getMethod()).append("]\n")
+				.append("Bean [").append(handlerMethod.getBean()).append("]\n");
 		return sb.toString();
 	}
 

spring-jms/src/main/java/org/springframework/jms/listener/endpoint/JmsMessageEndpointFactory.java

@@ -22,6 +22,8 @@ import javax.resource.ResourceException;
 import javax.resource.spi.UnavailableException;
 
 import org.springframework.jca.endpoint.AbstractMessageEndpointFactory;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 /**
  * JMS-specific implementation of the JCA 1.7
@@ -47,6 +49,7 @@ import org.springframework.jca.endpoint.AbstractMessageEndpointFactory;
  */
 public class JmsMessageEndpointFactory extends AbstractMessageEndpointFactory  {
 
+	@Nullable
 	private MessageListener messageListener;
 
 
@@ -61,6 +64,7 @@ public class JmsMessageEndpointFactory extends AbstractMessageEndpointFactory  {
 	 * Return the JMS MessageListener for this endpoint.
 	 */
 	protected MessageListener getMessageListener() {
+		Assert.state(messageListener != null, "No MessageListener set");
 		return this.messageListener;
 	}
 
@@ -90,16 +94,12 @@ public class JmsMessageEndpointFactory extends AbstractMessageEndpointFactory  {
 				}
 			}
 			try {
-				messageListener.onMessage(message);
+				getMessageListener().onMessage(message);
 			}
-			catch (RuntimeException ex) {
+			catch (RuntimeException | Error ex) {
 				onEndpointException(ex);
 				throw ex;
 			}
-			catch (Error err) {
-				onEndpointException(err);
-				throw err;
-			}
 			finally {
 				if (applyDeliveryCalls) {
 					try {
@@ -114,7 +114,7 @@ public class JmsMessageEndpointFactory extends AbstractMessageEndpointFactory  {
 
 		@Override
 		protected ClassLoader getEndpointClassLoader() {
-			return messageListener.getClass().getClassLoader();
+			return getMessageListener().getClass().getClassLoader();
 		}
 	}
 

spring-jms/src/main/java/org/springframework/jms/remoting/JmsInvokerServiceExporter.java

@@ -59,6 +59,7 @@ public class JmsInvokerServiceExporter extends RemoteInvocationBasedExporter
 
 	private boolean ignoreInvalidRequests = true;
 
+	@Nullable
 	private Object proxy;
 
 

spring-jms/src/main/java/org/springframework/jms/support/converter/MarshallingMessageConverter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -32,6 +32,7 @@ import javax.xml.transform.stream.StreamResult;
 import javax.xml.transform.stream.StreamSource;
 
 import org.springframework.beans.factory.InitializingBean;
+import org.springframework.lang.Nullable;
 import org.springframework.oxm.Marshaller;
 import org.springframework.oxm.Unmarshaller;
 import org.springframework.oxm.XmlMappingException;
@@ -51,8 +52,10 @@ import org.springframework.util.Assert;
  */
 public class MarshallingMessageConverter implements MessageConverter, InitializingBean {
 
+	@Nullable
 	private Marshaller marshaller;
 
+	@Nullable
 	private Unmarshaller unmarshaller;
 
 	private MessageType targetType = MessageType.BYTES;
@@ -108,6 +111,7 @@ public class MarshallingMessageConverter implements MessageConverter, Initializi
 	 * Set the {@link Marshaller} to be used by this message converter.
 	 */
 	public void setMarshaller(Marshaller marshaller) {
+		Assert.notNull(marshaller, "Marshaller must not be null");
 		this.marshaller = marshaller;
 	}
 
@@ -115,6 +119,7 @@ public class MarshallingMessageConverter implements MessageConverter, Initializi
 	 * Set the {@link Unmarshaller} to be used by this message converter.
 	 */
 	public void setUnmarshaller(Unmarshaller unmarshaller) {
+		Assert.notNull(unmarshaller, "Unmarshaller must not be null");
 		this.unmarshaller = unmarshaller;
 	}
 
@@ -148,6 +153,7 @@ public class MarshallingMessageConverter implements MessageConverter, Initializi
 	 */
 	@Override
 	public Message toMessage(Object object, Session session) throws JMSException, MessageConversionException {
+		Assert.state(this.marshaller != null, "No Marshaller set");
 		try {
 			switch (this.targetType) {
 				case TEXT:
@@ -158,10 +164,7 @@ public class MarshallingMessageConverter implements MessageConverter, Initializi
 					return marshalToMessage(object, session, this.marshaller, this.targetType);
 			}
 		}
-		catch (XmlMappingException ex) {
-			throw new MessageConversionException("Could not marshal [" + object + "]", ex);
-		}
-		catch (IOException ex) {
+		catch (XmlMappingException | IOException ex) {
 			throw new MessageConversionException("Could not marshal [" + object + "]", ex);
 		}
 	}
@@ -173,6 +176,7 @@ public class MarshallingMessageConverter implements MessageConverter, Initializi
 	 */
 	@Override
 	public Object fromMessage(Message message) throws JMSException, MessageConversionException {
+		Assert.state(this.unmarshaller != null, "No Unmarshaller set");
 		try {
 			if (message instanceof TextMessage) {
 				TextMessage textMessage = (TextMessage) message;