Consistent whitespace after imports

Update code to have a consistent number of new-line characters after
import statements.

spring-messaging/src/main/java/org/springframework/messaging/core/AbstractDestinationResolvingMessagingTemplate.java

@@ -20,7 +20,6 @@ import java.util.Map;
 import org.springframework.messaging.Message;
 import org.springframework.util.Assert;
 
-
 /**
  * Base class for a messaging template that can resolve String-based destinations.
  *

spring-messaging/src/main/java/org/springframework/messaging/core/AbstractMessageSendingTemplate.java

@@ -26,7 +26,6 @@ import org.springframework.messaging.support.converter.MessageConverter;
 import org.springframework.messaging.support.converter.SimpleMessageConverter;
 import org.springframework.util.Assert;
 
-
 /**
  * Base class for templates that support sending messages.
  *

spring-messaging/src/main/java/org/springframework/messaging/core/AbstractMessagingTemplate.java

@@ -20,7 +20,6 @@ import java.util.Map;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHeaders;
 
-
 /**
  * Base class for a messaging template that send and receive messages.
  *

spring-messaging/src/main/java/org/springframework/messaging/handler/method/AbstractExceptionHandlerMethodResolver.java

@@ -24,7 +24,6 @@ import java.lang.reflect.Method;
 import java.util.*;
 import java.util.concurrent.ConcurrentHashMap;
 
-
 /**
  * Cache exception handling method mappings and provide options to look up a method
  * that should handle an exception. If multiple methods match, they are sorted using

spring-messaging/src/main/java/org/springframework/messaging/handler/method/HandlerMethodReturnValueHandlerComposite.java

@@ -26,7 +26,6 @@ import org.springframework.core.MethodParameter;
 import org.springframework.messaging.Message;
 import org.springframework.util.Assert;
 
-
 /**
  * @author Rossen Stoyanchev
  * @since 4.0

spring-messaging/src/main/java/org/springframework/messaging/simp/BrokerAvailabilityEvent.java

@@ -18,7 +18,6 @@ package org.springframework.messaging.simp;
 
 import org.springframework.context.ApplicationEvent;
 
-
 /**
  * Event raised when a broker's availabilty changes
  *

spring-messaging/src/main/java/org/springframework/messaging/simp/config/StompBrokerRelayRegistration.java

@@ -20,7 +20,6 @@ import org.springframework.messaging.MessageChannel;
 import org.springframework.messaging.simp.stomp.StompBrokerRelayMessageHandler;
 import org.springframework.util.Assert;
 
-
 /**
  * Registration class for configuring a {@link StompBrokerRelayMessageHandler}.
  *