GH-1352: Fix Sonar Issues

Author: garyrussell

Diff for: spring-rabbit-stream/src/main/java/org/springframework/rabbit/stream/listener/StreamListenerContainer.java

@@ -106,7 +106,7 @@ public void setMessageConverter(StreamMessageConverter messageConverter) {
 	 * Customize the consumer builder before it is built.
 	 * @param consumerCustomizer the customizer.
 	 */
-	public void setConsumerCustomizer(java.util.function.Consumer<ConsumerBuilder> consumerCustomizer) {
+	public synchronized void setConsumerCustomizer(java.util.function.Consumer<ConsumerBuilder> consumerCustomizer) {
 		this.consumerCustomizer = consumerCustomizer;
 	}
 

Diff for: spring-rabbit/src/main/java/org/springframework/amqp/rabbit/listener/adapter/HandlerAdapter.java

@@ -63,7 +63,7 @@ public HandlerAdapter(DelegatingInvocableHandler delegatingHandler) {
 	 * @return the invocation result.
 	 * @throws Exception if one occurs.
 	 */
-	public InvocationResult invoke(Message<?> message, Object... providedArgs) throws Exception { // NOSONAR
+	public InvocationResult invoke(@Nullable Message<?> message, Object... providedArgs) throws Exception { // NOSONAR
 		if (this.invokerHandlerMethod != null) {
 			return new InvocationResult(this.invokerHandlerMethod.invoke(message, providedArgs),
 					null, this.invokerHandlerMethod.getMethod().getGenericReturnType(),