Sonar fixes

Critical smells `0.s.i.r*`

* Polishing - PR Comments.

spring-integration-core/src/main/java/org/springframework/integration/context/IntegrationObjectSupport.java

@@ -17,6 +17,7 @@
 package org.springframework.integration.context;
 
 import java.util.Properties;
+import java.util.UUID;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -44,7 +45,9 @@ import org.springframework.integration.support.utils.IntegrationUtils;
 import org.springframework.messaging.MessageChannel;
 import org.springframework.messaging.core.DestinationResolver;
 import org.springframework.scheduling.TaskScheduler;
+import org.springframework.util.AlternativeJdkIdGenerator;
 import org.springframework.util.Assert;
+import org.springframework.util.IdGenerator;
 import org.springframework.util.StringUtils;
 
 /**
@@ -68,10 +71,12 @@ public abstract class IntegrationObjectSupport implements BeanNameAware, NamedCo
 
 	protected static final ExpressionParser EXPRESSION_PARSER = new SpelExpressionParser();
 
+	private static final IdGenerator idGenerator = new AlternativeJdkIdGenerator(); // NOSONAR lower case
+
 	/**
 	 * Logger that is available to subclasses
 	 */
-	protected final Log logger = LogFactory.getLog(getClass());
+	protected final Log logger = LogFactory.getLog(getClass()); // NOSONAR protected
 
 	private final ConversionService defaultConversionService = DefaultConversionService.getSharedInstance();
 
@@ -312,4 +317,8 @@ public abstract class IntegrationObjectSupport implements BeanNameAware, NamedCo
 		return (this.beanName != null) ? this.beanName : super.toString();
 	}
 
+	public static UUID generateId() {
+		return idGenerator.generateId();
+	}
+
 }

spring-integration-core/src/main/java/org/springframework/integration/router/AbstractMappingMessageRouter.java

@@ -293,7 +293,10 @@ public abstract class AbstractMappingMessageRouter extends AbstractMessageRouter
 				addToCollection(channels, (Collection<?>) channelKey, message);
 			}
 			else if (getRequiredConversionService().canConvert(channelKey.getClass(), String.class)) {
-				addChannelFromString(channels, getConversionService().convert(channelKey, String.class), message);
+				String converted = getConversionService().convert(channelKey, String.class);
+				if (converted != null) {
+					addChannelFromString(channels, converted, message);
+				}
 			}
 			else {
 				throw new MessagingException("unsupported return type for router [" + channelKey.getClass() + "]");

spring-integration-core/src/main/java/org/springframework/integration/router/AbstractMessageRouter.java

@@ -17,6 +17,7 @@
 package org.springframework.integration.router;
 
 import java.util.Collection;
+import java.util.UUID;
 
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.support.DefaultConversionService;
@@ -171,24 +172,20 @@ public abstract class AbstractMessageRouter extends AbstractMessageHandler imple
 			int sequenceSize = results.size();
 			int sequenceNumber = 1;
 			for (MessageChannel channel : results) {
-				final Message<?> messageToSend =
-						!this.applySequence ? message : (this.getMessageBuilderFactory()
+				final Message<?> messageToSend;
+				if (!this.applySequence) {
+					messageToSend = message;
+				}
+				else {
+					UUID id = message.getHeaders().getId();
+					messageToSend = getMessageBuilderFactory()
 								.fromMessage(message)
-								.pushSequenceDetails(message.getHeaders().getId(), sequenceNumber++, sequenceSize)
-								.build());
+								.pushSequenceDetails(id == null ? generateId() : id,
+										sequenceNumber++, sequenceSize)
+								.build();
+				}
 				if (channel != null) {
-					try {
-						this.messagingTemplate.send(channel, messageToSend);
-						sent = true;
-					}
-					catch (MessagingException e) {
-						if (!this.ignoreSendFailures) {
-							throw e;
-						}
-						else if (this.logger.isDebugEnabled()) {
-							this.logger.debug(e);
-						}
-					}
+					sent |= doSend(channel, messageToSend);
 				}
 			}
 		}
@@ -204,4 +201,18 @@ public abstract class AbstractMessageRouter extends AbstractMessageHandler imple
 		}
 	}
 
+	private boolean doSend(MessageChannel channel, final Message<?> messageToSend) {
+		try {
+			this.messagingTemplate.send(channel, messageToSend);
+			return true;
+		}
+		catch (MessagingException e) {
+			if (!this.ignoreSendFailures) {
+				throw e;
+			}
+			this.logger.debug("Send failure ignored", e);
+			return false;
+		}
+	}
+
 }