INT-2166: Add SecurityContext Propagation

JIRA: https://jira.spring.io/browse/INT-2166

* Introduce `ThreadStatePropagationChannelInterceptor` based on the `ExecutorChannelInterceptor`
* Add `SecurityContextPropagationChannelInterceptor`,`SecurityContextCleanupChannelInterceptor`
* Introduce `AbstractExecutorChannel` to utilize `ExecutorChannelInterceptor` logic
* Introduce `MessageHandlingTaskDecorator` to avoid package tangle from `dispatcher` and `channel`
* Introduce `SecurityContextCleanupAdvice` for those cases when we don't get deal with `MessageChannel`s already, but want to have proper way to cleanup `SecurityContext`
* Make `GlobalChannelInterceptorProcessor` as `SmartInitializingSingleton` to avoid `phase` conflicts.
* Fix `MessagingAnnotationPostProcessor` to use `beanFactory.initializeBean(endpoint, endpointBeanName);` instead of manual `start()` invocation bypassing the `phase` logic, hence having a bug, when endpoints have been started very early
* Optimise `AbstractPollableChannel` to use `size` field from `ChannelInterceptorList` instead of `size()` from `Collection<?>`
* Fix `AnnotatedEndpointActivationTests` extracting separate component for annotation configuration instead of using test class directly. This caused very late Messaging Annotations process on that class
* Fix typo in the `spring-integration-jdbc-4.2.xsd`
* Remove some `SOUT`s throughout the project

TODO Docs

PR Comments:

* Remove redundant `AbstractExecutorChannel#executorInterceptors` and make logic based on the `super.interceptors`
 * Fix wrong imports order
 * JavaDocs for `ThreadStatePropagationChannelInterceptor`
 * Docs for `SecurityContext` propagation

INT-3593: Fix FTP PartialSuccess Tests

JIRA: https://jira.spring.io/browse/INT-3593

Sort the files for the MPUT tests.

INT-2166: Add SecurityContext Propagation

JIRA: https://jira.spring.io/browse/INT-2166

* Introduce `ThreadStatePropagationChannelInterceptor` based on the `ExecutorChannelInterceptor`
* Add `SecurityContextPropagationChannelInterceptor`,`SecurityContextCleanupChannelInterceptor`
* Introduce `AbstractExecutorChannel` to utilize `ExecutorChannelInterceptor` logic
* Introduce `MessageHandlingTaskDecorator` to avoid package tangle from `dispatcher` and `channel`
* Introduce `SecurityContextCleanupAdvice` for those cases when we don't get deal with `MessageChannel`s already, but want to have proper way to cleanup `SecurityContext`
* Make `GlobalChannelInterceptorProcessor` as `SmartInitializingSingleton` to avoid `phase` conflicts.
* Fix `MessagingAnnotationPostProcessor` to use `beanFactory.initializeBean(endpoint, endpointBeanName);` instead of manual `start()` invocation bypassing the `phase` logic, hence having a bug, when endpoints have been started very early
* Optimise `AbstractPollableChannel` to use `size` field from `ChannelInterceptorList` instead of `size()` from `Collection<?>`
* Fix `AnnotatedEndpointActivationTests` extracting separate component for annotation configuration instead of using test class directly. This caused very late Messaging Annotations process on that class
* Fix typo in the `spring-integration-jdbc-4.2.xsd`
* Remove some `SOUT`s throughout the project

TODO Docs

PR Comments:

* Remove redundant `AbstractExecutorChannel#executorInterceptors` and make logic based on the `super.interceptors`
 * Fix wrong imports order
 * JavaDocs for `ThreadStatePropagationChannelInterceptor`
 * Docs for `SecurityContext` propagation

Doc Polishing

Address PR comments

Address PR comments

* Extract `ExecutorChannelInterceptor` logic in the `PollingConsumer`
to have an ability to invoke `afterMessageHandled()` on the TaskScheduler's Thread
for example for the `SecurityContext` clean up
* Get rid of all that redundant "clean up" stuff
* Docs polishing

Fix `NPE` in the `PollingConsumer`

Introduce `ExecutorChannelInterceptorAware` to avoid iterators on each message

Polishing; Docs, Sonar

spring-integration-security/src/main/java/org/springframework/integration/security/channel/ChannelAccessPolicy.java

@@ -23,7 +23,7 @@ import org.springframework.security.access.ConfigAttribute;
 /**
  * Interface to encapsulate {@link ConfigAttribute}s for secured channel
  * send and receive operations.
- * 
+ *
  * @author Oleg Zhurakousky
  * @since 2.0
  */

spring-integration-security/src/main/java/org/springframework/integration/security/channel/ChannelSecurityInterceptor.java

@@ -20,6 +20,7 @@ import java.lang.reflect.Method;
 
 import org.aopalliance.intercept.MethodInterceptor;
 import org.aopalliance.intercept.MethodInvocation;
+
 import org.springframework.security.access.SecurityMetadataSource;
 import org.springframework.security.access.intercept.AbstractSecurityInterceptor;
 import org.springframework.security.access.intercept.InterceptorStatusToken;

spring-integration-security/src/main/java/org/springframework/integration/security/channel/SecurityContextPropagationChannelInterceptor.java

@@ -0,0 +1,95 @@
+/*
+ * Copyright 2015 the original author or authors.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+package org.springframework.integration.security.channel;
+
+import org.springframework.aop.support.AopUtils;
+import org.springframework.integration.channel.DirectChannel;
+import org.springframework.integration.channel.interceptor.ThreadStatePropagationChannelInterceptor;
+import org.springframework.messaging.Message;
+import org.springframework.messaging.MessageChannel;
+import org.springframework.messaging.MessageHandler;
+import org.springframework.messaging.support.ExecutorChannelInterceptor;
+import org.springframework.security.core.Authentication;
+import org.springframework.security.core.context.SecurityContext;
+import org.springframework.security.core.context.SecurityContextHolder;
+
+/**
+ * The {@link ExecutorChannelInterceptor} implementation responsible for
+ * the {@link SecurityContext} propagation from one message flow's thread to another
+ * through the {@link MessageChannel}s involved in the flow.
+ * <p>
+ * In addition this interceptor cleans up (restores) the {@link SecurityContext}
+ * in the containers Threads for channels like
+ * {@link org.springframework.integration.channel.ExecutorChannel}
+ * and {@link org.springframework.integration.channel.QueueChannel}.
+ *
+ * @author Artem Bilan
+ * @see ThreadStatePropagationChannelInterceptor
+ * @since 4.2
+ */
+public class SecurityContextPropagationChannelInterceptor
+		extends ThreadStatePropagationChannelInterceptor<Authentication> {
+
+	private final static SecurityContext EMPTY_CONTEXT = SecurityContextHolder.createEmptyContext();
+
+	private static final ThreadLocal<SecurityContext> ORIGINAL_CONTEXT = new ThreadLocal<SecurityContext>();
+
+	@Override
+	public void afterMessageHandled(Message<?> message, MessageChannel channel, MessageHandler handler, Exception ex) {
+		cleanup();
+	}
+
+	@Override
+	protected Authentication obtainPropagatingContext(Message<?> message, MessageChannel channel) {
+		if (!DirectChannel.class.isAssignableFrom(AopUtils.getTargetClass(channel))) {
+			return SecurityContextHolder.getContext().getAuthentication();
+		}
+		return null;
+	}
+
+	@Override
+	protected void populatePropagatedContext(Authentication authentication, Message<?> message,
+											 MessageChannel channel) {
+		if (authentication != null) {
+			SecurityContext currentContext = SecurityContextHolder.getContext();
+
+			ORIGINAL_CONTEXT.set(currentContext);
+
+			SecurityContext context = SecurityContextHolder.createEmptyContext();
+			context.setAuthentication(authentication);
+			SecurityContextHolder.setContext(context);
+		}
+	}
+
+	public static void cleanup() {
+		SecurityContext originalContext = ORIGINAL_CONTEXT.get();
+
+		try {
+			if (originalContext == null || EMPTY_CONTEXT.equals(originalContext)) {
+				SecurityContextHolder.clearContext();
+				ORIGINAL_CONTEXT.remove();
+			}
+			else {
+				SecurityContextHolder.setContext(originalContext);
+			}
+		}
+		catch (Throwable t) {
+			SecurityContextHolder.clearContext();
+		}
+	}
+
+}