Fix Checkstyle violations

https://build.spring.io/browse/INT-SI43X-173/

spring-integration-core/src/main/java/org/springframework/integration/gateway/GatewayMethodInboundMessageMapper.java

@@ -47,7 +47,6 @@ import org.springframework.integration.support.MessageBuilderFactory;
 import org.springframework.integration.util.MessagingAnnotationUtils;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessagingException;
-import org.springframework.messaging.core.GenericMessagingTemplate;
 import org.springframework.messaging.handler.annotation.Header;
 import org.springframework.messaging.handler.annotation.Headers;
 import org.springframework.messaging.handler.annotation.Payload;

spring-integration-core/src/main/java/org/springframework/integration/gateway/GatewayProxyFactoryBean.java

@@ -40,7 +40,6 @@ import org.springframework.beans.TypeConverter;
 import org.springframework.beans.factory.BeanClassLoaderAware;
 import org.springframework.beans.factory.BeanDefinitionStoreException;
 import org.springframework.beans.factory.BeanFactory;
-import org.springframework.beans.factory.BeanInitializationException;
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.core.MethodParameter;
 import org.springframework.core.convert.ConversionService;
@@ -50,7 +49,6 @@ import org.springframework.core.task.SimpleAsyncTaskExecutor;
 import org.springframework.core.task.support.TaskExecutorAdapter;
 import org.springframework.expression.Expression;
 import org.springframework.expression.common.LiteralExpression;
-import org.springframework.expression.spel.standard.SpelExpressionParser;
 import org.springframework.integration.annotation.Gateway;
 import org.springframework.integration.annotation.GatewayHeader;
 import org.springframework.integration.context.IntegrationProperties;

spring-integration-core/src/main/java/org/springframework/integration/transformer/ContentEnricher.java

@@ -21,7 +21,6 @@ import java.util.HashMap;
 import java.util.Map;
 
 import org.springframework.beans.factory.BeanFactoryAware;
-import org.springframework.beans.factory.BeanInitializationException;
 import org.springframework.context.Lifecycle;
 import org.springframework.expression.EvaluationContext;
 import org.springframework.expression.Expression;

spring-integration-core/src/main/java/org/springframework/integration/transformer/HeaderEnricher.java

@@ -20,11 +20,7 @@ import java.util.HashMap;
 import java.util.Map;
 import java.util.Map.Entry;
 
-import org.apache.commons.logging.Log;
-import org.apache.commons.logging.LogFactory;
-
 import org.springframework.beans.factory.BeanFactoryAware;
-import org.springframework.beans.factory.BeanInitializationException;
 import org.springframework.beans.factory.BeanNameAware;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.integration.context.IntegrationObjectSupport;
@@ -162,8 +158,8 @@ public class HeaderEnricher extends IntegrationObjectSupport implements Transfor
 			if (checkReadOnlyHeaders &&
 					(MessageHeaders.ID.equals(entry.getKey()) || MessageHeaders.TIMESTAMP.equals(entry.getKey()))) {
 				this.logger.warn("HeaderEnricher cannot override 'id' and 'timestamp' read-only headers.\n" +
-								"Wrong 'headersToAdd' [" + this.headersToAdd
-								+ "] configuration for " + getComponentName());
+						"Wrong 'headersToAdd' [" + this.headersToAdd
+						+ "] configuration for " + getComponentName());
 			}
 
 			HeaderValueMessageProcessor<?> processor = entry.getValue();

spring-integration-core/src/main/java/org/springframework/integration/transformer/HeaderFilter.java

@@ -18,7 +18,6 @@ package org.springframework.integration.transformer;
 
 import java.util.Arrays;
 
-import org.springframework.beans.factory.BeanInitializationException;
 import org.springframework.integration.context.IntegrationObjectSupport;
 import org.springframework.integration.support.AbstractIntegrationMessageBuilder;
 import org.springframework.integration.support.DefaultMessageBuilderFactory;

spring-integration-core/src/test/java/org/springframework/integration/handler/MethodInvokingHeaderEnricherTests.java

@@ -16,24 +16,16 @@
 
 package org.springframework.integration.handler;
 
-import static org.hamcrest.Matchers.containsString;
-import static org.hamcrest.Matchers.instanceOf;
 import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertThat;
-import static org.junit.Assert.fail;
 
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 
 import org.junit.Test;
 
-import org.springframework.beans.factory.BeanInitializationException;
 import org.springframework.integration.support.MessageBuilder;
 import org.springframework.integration.transformer.HeaderEnricher;
-import org.springframework.integration.transformer.support.StaticHeaderValueMessageProcessor;
 import org.springframework.messaging.Message;
-import org.springframework.messaging.MessageHeaders;
 import org.springframework.messaging.handler.annotation.Payload;
 
 /**

spring-integration-core/src/test/java/org/springframework/integration/transformer/ContentEnricherTests.java

@@ -18,7 +18,6 @@ package org.springframework.integration.transformer;
 
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.equalToIgnoringCase;
-import static org.hamcrest.Matchers.instanceOf;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotSame;
@@ -28,7 +27,6 @@ import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 import static org.mockito.Mockito.mock;
 
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -36,7 +34,6 @@ import org.junit.Before;
 import org.junit.Test;
 
 import org.springframework.beans.factory.BeanFactory;
-import org.springframework.beans.factory.BeanInitializationException;
 import org.springframework.expression.Expression;
 import org.springframework.expression.common.LiteralExpression;
 import org.springframework.expression.spel.standard.SpelExpressionParser;
@@ -50,11 +47,9 @@ import org.springframework.integration.endpoint.PollingConsumer;
 import org.springframework.integration.handler.AbstractReplyProducingMessageHandler;
 import org.springframework.integration.handler.ReplyRequiredException;
 import org.springframework.integration.support.MessageBuilder;
-import org.springframework.integration.transformer.support.StaticHeaderValueMessageProcessor;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageDeliveryException;
 import org.springframework.messaging.MessageHandlingException;
-import org.springframework.messaging.MessageHeaders;
 import org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler;
 import org.springframework.scheduling.support.PeriodicTrigger;
 

spring-integration-core/src/test/java/org/springframework/integration/transformer/HeaderFilterTests.java

@@ -16,14 +16,11 @@
 
 package org.springframework.integration.transformer;
 
-import static org.hamcrest.Matchers.containsString;
-import static org.hamcrest.Matchers.instanceOf;
 import static org.hamcrest.Matchers.not;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertThat;
-import static org.junit.Assert.fail;
 import static org.mockito.Mockito.mock;
 import static org.springframework.integration.test.matcher.HeaderMatcher.hasHeaderKey;
 
@@ -33,7 +30,6 @@ import java.util.UUID;
 import org.junit.Test;
 
 import org.springframework.beans.factory.BeanFactory;
-import org.springframework.beans.factory.BeanInitializationException;
 import org.springframework.integration.IntegrationMessageHeaderAccessor;
 import org.springframework.integration.channel.QueueChannel;
 import org.springframework.integration.support.MessageBuilder;