Fix new Sonar Smells

* Change `whats-new.adoc#x5.2-behavior` to point for the whole
`5.1-to-5.2-Migration-Guide`

Author: artembilan

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

@@ -290,15 +290,14 @@ private void incrementReceiveCounter() {
 	}
 
 	private CounterFacade buildReceiveCounter() {
-		CounterFacade counterFacade = this.metricsCaptor
+		return this.metricsCaptor
 				.counterBuilder(RECEIVE_COUNTER_NAME)
 				.tag("name", getComponentName() == null ? "unknown" : getComponentName())
 				.tag("type", "channel")
 				.tag("result", "success")
 				.tag("exception", "none")
 				.description("Messages received")
 				.build();
-		return counterFacade;
 	}
 
 	@Override

spring-integration-core/src/main/java/org/springframework/integration/transaction/ExpressionEvaluatingTransactionSynchronizationProcessor.java

@@ -16,6 +16,7 @@
 
 package org.springframework.integration.transaction;
 
+import java.util.Map;
 import java.util.Map.Entry;
 
 import org.springframework.expression.EvaluationContext;
@@ -142,28 +143,7 @@ private void doProcess(IntegrationResourceHolder holder, Expression expression,
 				EvaluationContext evaluationContextToUse = prepareEvaluationContextToUse(holder);
 				Object value = expression.getValue(evaluationContextToUse, message);
 				if (value != null && messageChannel != null) {
-					if (logger.isDebugEnabled()) {
-						logger.debug("Sending expression result message to " + messageChannel + " " +
-								"as part of '" + expressionType + "' transaction synchronization");
-					}
-					Message<?> spelResultMessage = null;
-					try {
-						if (value instanceof Message<?>) {
-							spelResultMessage = (Message<?>) value;
-						}
-						else {
-							spelResultMessage =
-									getMessageBuilderFactory()
-											.withPayload(value)
-											.copyHeaders(message.getHeaders())
-											.build();
-						}
-
-						sendMessage(messageChannel, spelResultMessage);
-					}
-					catch (Exception e) {
-						logger.error("Failed to send " + expressionType + " evaluation result " + spelResultMessage, e);
-					}
+					sendMessageForExpressionResult(value, message.getHeaders(), messageChannel, expressionType);
 				}
 				else {
 					if (logger.isTraceEnabled()) {
@@ -189,6 +169,33 @@ else if (messageChannel != null) {
 		}
 	}
 
+	private void sendMessageForExpressionResult(Object value, Map<String, ?> headers,
+			MessageChannel messageChannel, String expressionType) {
+
+		if (logger.isDebugEnabled()) {
+			logger.debug("Sending expression result message to " + messageChannel + " " +
+					"as part of '" + expressionType + "' transaction synchronization");
+		}
+		Message<?> spelResultMessage = null;
+		try {
+			if (value instanceof Message<?>) {
+				spelResultMessage = (Message<?>) value;
+			}
+			else {
+				spelResultMessage =
+						getMessageBuilderFactory()
+								.withPayload(value)
+								.copyHeaders(headers)
+								.build();
+			}
+
+			sendMessage(messageChannel, spelResultMessage);
+		}
+		catch (Exception e) {
+			logger.error("Failed to send " + expressionType + " evaluation result " + spelResultMessage, e);
+		}
+	}
+
 	private void sendMessage(MessageChannel channel, Message<?> message) {
 		channel.send(message, 0);
 	}

src/reference/asciidoc/whats-new.adoc

@@ -20,7 +20,7 @@ If you are interested in more details, see the Issue Tracker tickets that were r
 [[x5.2-behavior]]
 === Behavior Changes
 
-See the https://github.com/spring-projects/spring-integration/wiki/Spring-Integration-5.1-to-5.2-Migration-Guide#dsl-publishsubscribechannel-behavior-change[Migration Guide] about a behavior change when using `publishSubscribeChannel` within a dynamically registered DSL integration flow.
+See the https://github.com/spring-projects/spring-integration/wiki/Spring-Integration-5.1-to-5.2-Migration-Guide[Migration Guide] about behavior changes in this version.
 
 [[x5.2-new-components]]
 === New Components