Remove Legacy Metrics

- Simplify MBeans - instead of wrapping to expose lifecycle methods,
  implement `ManageableLifecycle`. Register an additional MBean for
  polled endpoints to control the lifecycle.

* Polishing

- Move `QueueChannel` `@ManagedAttribute`s to `QueueChannelOperations`
- Make all `AbstractEndpoints` `IntegrationManagedResource`s and remove `ManagedEndpoint`
  to allow exposure of any `@Managed*` methods (including those on `Pausable`)
- Revert to `Lifecycle` for classes that are not related to endpoints
- Remove legacy metrics from docs

spring-integration-file/src/main/java/org/springframework/integration/file/FileReadingMessageSource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -47,6 +47,7 @@ import org.springframework.integration.file.filters.DiscardAwareFileListFilter;
 import org.springframework.integration.file.filters.FileListFilter;
 import org.springframework.integration.file.filters.ResettableFileListFilter;
 import org.springframework.integration.support.AbstractIntegrationMessageBuilder;
+import org.springframework.integration.support.management.ManageableLifecycle;
 import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.util.Assert;
@@ -91,7 +92,7 @@ import org.springframework.util.Assert;
  * @author Steven Pearce
  */
 public class FileReadingMessageSource extends AbstractMessageSource<File>
-		implements Lifecycle {
+		implements ManageableLifecycle {
 
 	private static final int DEFAULT_INTERNAL_QUEUE_CAPACITY = 5;
 
@@ -416,7 +417,7 @@ public class FileReadingMessageSource extends AbstractMessageSource<File>
 
 	}
 
-	private class WatchServiceDirectoryScanner extends DefaultDirectoryScanner implements Lifecycle {
+	private class WatchServiceDirectoryScanner extends DefaultDirectoryScanner implements ManageableLifecycle {
 
 		private final ConcurrentMap<Path, WatchKey> pathKeys = new ConcurrentHashMap<>();
 

spring-integration-file/src/main/java/org/springframework/integration/file/FileWritingMessageHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -45,7 +45,6 @@ import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 
 import org.springframework.beans.factory.BeanFactoryAware;
-import org.springframework.context.Lifecycle;
 import org.springframework.expression.Expression;
 import org.springframework.expression.common.LiteralExpression;
 import org.springframework.expression.spel.support.StandardEvaluationContext;
@@ -58,6 +57,7 @@ import org.springframework.integration.handler.MessageTriggerAction;
 import org.springframework.integration.support.locks.DefaultLockRegistry;
 import org.springframework.integration.support.locks.LockRegistry;
 import org.springframework.integration.support.locks.PassThruLockRegistry;
+import org.springframework.integration.support.management.ManageableLifecycle;
 import org.springframework.integration.support.utils.IntegrationUtils;
 import org.springframework.integration.util.WhileLockedProcessor;
 import org.springframework.messaging.Message;
@@ -109,7 +109,7 @@ import org.springframework.util.StringUtils;
  * @author Alen Turkovic
  */
 public class FileWritingMessageHandler extends AbstractReplyProducingMessageHandler
-		implements Lifecycle, MessageTriggerAction {
+		implements ManageableLifecycle, MessageTriggerAction {
 
 	private static final int DEFAULT_BUFFER_SIZE = 8192;
 

spring-integration-file/src/main/java/org/springframework/integration/file/remote/AbstractRemoteFileStreamingMessageSource.java

@@ -29,7 +29,6 @@ import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
 
-import org.springframework.context.Lifecycle;
 import org.springframework.expression.Expression;
 import org.springframework.expression.common.LiteralExpression;
 import org.springframework.integration.IntegrationMessageHeaderAccessor;
@@ -40,6 +39,7 @@ import org.springframework.integration.file.filters.ResettableFileListFilter;
 import org.springframework.integration.file.filters.ReversibleFileListFilter;
 import org.springframework.integration.file.remote.session.Session;
 import org.springframework.integration.file.support.FileUtils;
+import org.springframework.integration.support.management.ManageableLifecycle;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
@@ -56,7 +56,7 @@ import org.springframework.util.ObjectUtils;
  *
  */
 public abstract class AbstractRemoteFileStreamingMessageSource<F>
-		extends AbstractFetchLimitingMessageSource<InputStream> implements Lifecycle {
+		extends AbstractFetchLimitingMessageSource<InputStream> implements ManageableLifecycle {
 
 	private final RemoteFileTemplate<F> remoteFileTemplate;
 

spring-integration-file/src/main/java/org/springframework/integration/file/remote/synchronizer/AbstractInboundFileSynchronizingMessageSource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -25,7 +25,6 @@ import java.util.Comparator;
 import java.util.regex.Pattern;
 
 import org.springframework.beans.factory.BeanInitializationException;
-import org.springframework.context.Lifecycle;
 import org.springframework.integration.endpoint.AbstractFetchLimitingMessageSource;
 import org.springframework.integration.file.DefaultDirectoryScanner;
 import org.springframework.integration.file.DirectoryScanner;
@@ -37,6 +36,7 @@ import org.springframework.integration.file.filters.FileSystemPersistentAcceptOn
 import org.springframework.integration.file.filters.RegexPatternFileListFilter;
 import org.springframework.integration.metadata.SimpleMetadataStore;
 import org.springframework.integration.support.AbstractIntegrationMessageBuilder;
+import org.springframework.integration.support.management.ManageableLifecycle;
 import org.springframework.util.Assert;
 
 /**
@@ -65,7 +65,7 @@ import org.springframework.util.Assert;
  */
 public abstract class AbstractInboundFileSynchronizingMessageSource<F>
 		extends AbstractFetchLimitingMessageSource<File>
-		implements Lifecycle {
+		implements ManageableLifecycle {
 
 	/**
 	 * An implementation that will handle the chores of actually connecting to and synchronizing