GH-2748: More bean definitions into exceptions

Fixes https://github.com/spring-projects/spring-integration/issues/2748

* Refactor more `MessageHandlingException`s to include `this` into an
exception message
* Revert using `MessagingException` in some places which really are not
about messaging.
This helps to wrap them into `MessageHandlingException` later in the
`MessageHandler` for the `BeanDefinition` reference
* Remove `volatile` from configuration properties in the affected
classes
* Remove already deprecated `JmsOutboundGateway.setPriority()`
* Add `resource` and `source` for `BeanDefinition` in the
`AbstractChannelAdapterParser` & `AbstractInboundGatewayParser`
* Document the feature

spring-integration-xml/src/main/java/org/springframework/integration/xml/selector/XmlValidatingMessageSelector.java

@@ -17,6 +17,7 @@
 package org.springframework.integration.xml.selector;
 
 import java.io.IOException;
+import java.io.UncheckedIOException;
 import java.util.Arrays;
 
 import org.apache.commons.logging.Log;
@@ -30,7 +31,6 @@ import org.springframework.integration.xml.AggregatedXmlMessageValidationExcepti
 import org.springframework.integration.xml.DefaultXmlPayloadConverter;
 import org.springframework.integration.xml.XmlPayloadConverter;
 import org.springframework.messaging.Message;
-import org.springframework.messaging.MessageHandlingException;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
@@ -65,7 +65,7 @@ public class XmlValidatingMessageSelector implements MessageSelector {
 
 	}
 
-	private final Log logger = LogFactory.getLog(getClass());
+	private static final Log LOGGER = LogFactory.getLog(XmlValidatingMessageSelector.class);
 
 	private final XmlValidator xmlValidator;
 
@@ -110,7 +110,6 @@ public class XmlValidatingMessageSelector implements MessageSelector {
 
 	/**
 	 * Specify the Converter to use when converting payloads prior to validation.
-	 *
 	 * @param converter The payload converter.
 	 */
 	public void setConverter(XmlPayloadConverter converter) {
@@ -120,21 +119,22 @@ public class XmlValidatingMessageSelector implements MessageSelector {
 
 	@Override
 	public boolean accept(Message<?> message) {
-		SAXParseException[] validationExceptions = null;
+		SAXParseException[] validationExceptions;
 		try {
 			validationExceptions = this.xmlValidator.validate(this.converter.convertToSource(message.getPayload()));
 		}
-		catch (Exception e) {
-			throw new MessageHandlingException(message, e);
+		catch (IOException e) {
+			throw new UncheckedIOException(e);
 		}
 		boolean validationSuccess = ObjectUtils.isEmpty(validationExceptions);
 		if (!validationSuccess) {
+			String exceptionMessage = "Message was rejected due to XML Validation errors";
 			if (this.throwExceptionOnRejection) {
-				throw new MessageRejectedException(message, "Message was rejected due to XML Validation errors",
+				throw new MessageRejectedException(message, exceptionMessage,
 						new AggregatedXmlMessageValidationException(Arrays.asList(validationExceptions)));
 			}
-			else if (this.logger.isInfoEnabled()) {
-				this.logger.info("Message was rejected due to XML Validation errors",
+			else if (LOGGER.isInfoEnabled()) {
+				LOGGER.info(exceptionMessage,
 						new AggregatedXmlMessageValidationException(Arrays.asList(validationExceptions)));
 			}
 		}

spring-integration-xml/src/main/java/org/springframework/integration/xml/splitter/XPathMessageSplitter.java

@@ -210,13 +210,13 @@ public class XPathMessageSplitter extends AbstractMessageSplitter {
 	protected Object splitMessage(Message<?> message) {
 		try {
 			Object payload = message.getPayload();
-			Object result = null;
+			Object result;
 			if (payload instanceof Node) {
 				result = splitNode((Node) payload);
 			}
 			else {
 				Document document = this.xmlPayloadConverter.convertToDocument(payload);
-				Assert.notNull(document, "unsupported payload type [" + payload.getClass().getName() + "]");
+				Assert.notNull(document, () -> "unsupported payload type [" + payload.getClass().getName() + "]");
 				result = splitDocument(document);
 			}
 			return result;
@@ -226,7 +226,7 @@ public class XPathMessageSplitter extends AbstractMessageSplitter {
 		}
 		catch (Exception ex) {
 			throw IntegrationUtils.wrapInHandlingExceptionIfNecessary(message,
-					() -> "Failed to split Message payload", ex);
+					() -> "Failed to split Message payload in the [" + this + ']', ex);
 		}
 	}
 
@@ -369,9 +369,7 @@ public class XPathMessageSplitter extends AbstractMessageSplitter {
 
 		private final Iterator<Node> delegate;
 
-		TransformFunctionIterator(Iterator<Node> delegate,
-				Function<? super Node, ? extends String> function) {
-
+		TransformFunctionIterator(Iterator<Node> delegate, Function<? super Node, ? extends String> function) {
 			super(null, delegate, function);
 			this.delegate = delegate;
 		}