GH-8586: Deprecate IntegrationComponentSpec.get() (#8594)

* GH-8586: Deprecate IntegrationComponentSpec.get()

Fixes https://github.com/spring-projects/spring-integration/issues/8586

The `IntegrationComponentSpec` is not a plain wrapper around single component.
Sometimes it comes with several components where all of them must be registered
as beans.
If `IntegrationComponentSpec.get()` is called from end-user code, we may lose
other related components, for example filters in the `FileInboundChannelAdapterSpec`.

* Deprecate `IntegrationComponentSpec.get()` with no-op for end-user,
rather encourage to leave it as is and let the framework take care about its lifecycle
and related components registration
* Fix `IntegrationComponentSpec` logic to deal as a simple `FactoryBean` instead of
extra overhead via `AbstractFactoryBean`
* Use `IntegrationComponentSpec.getObject()` in the framework code where `get()` was called
* Fix tests to expose `IntegrationComponentSpec` as beans instead of previously called `get()`
* Some other clean up and typos fixes in the affected classes
* Document the change

* * Revert `ObjectStringMapBuilder` in the `KafkaInboundGatewaySpec.getComponentsToRegister()`

* Fix language in docs

Co-authored-by: Gary Russell <grussell@vmware.com>

* * Remove trailing whitespace in the `ScriptMessageSourceSpec`

---------

Co-authored-by: Gary Russell <grussell@vmware.com>

spring-integration-ip/src/main/java/org/springframework/integration/ip/dsl/TcpInboundChannelAdapterSpec.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 the original author or authors.
+ * Copyright 2016-2023 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.
@@ -56,7 +56,7 @@ public class TcpInboundChannelAdapterSpec
 	 */
 	protected TcpInboundChannelAdapterSpec(AbstractConnectionFactorySpec<?, ?> connectionFactorySpec) {
 		super(new TcpReceivingChannelAdapter());
-		this.connectionFactory = connectionFactorySpec.get();
+		this.connectionFactory = connectionFactorySpec.getObject();
 		this.target.setConnectionFactory(this.connectionFactory);
 	}
 
@@ -94,7 +94,7 @@ public class TcpInboundChannelAdapterSpec
 	public Map<Object, String> getComponentsToRegister() {
 		return this.connectionFactory != null
 				? Collections.singletonMap(this.connectionFactory, this.connectionFactory.getComponentName())
-				: null;
+				: Collections.emptyMap();
 	}
 
 }

spring-integration-ip/src/main/java/org/springframework/integration/ip/dsl/TcpInboundGatewaySpec.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 the original author or authors.
+ * Copyright 2016-2023 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.
@@ -55,7 +55,7 @@ public class TcpInboundGatewaySpec extends MessagingGatewaySpec<TcpInboundGatewa
 	 */
 	protected TcpInboundGatewaySpec(AbstractConnectionFactorySpec<?, ?> connectionFactorySpec) {
 		super(new TcpInboundGateway());
-		this.connectionFactory = connectionFactorySpec.get();
+		this.connectionFactory = connectionFactorySpec.getObject();
 		this.target.setConnectionFactory(this.connectionFactory);
 	}
 
@@ -93,7 +93,7 @@ public class TcpInboundGatewaySpec extends MessagingGatewaySpec<TcpInboundGatewa
 	public Map<Object, String> getComponentsToRegister() {
 		return this.connectionFactory != null
 				? Collections.singletonMap(this.connectionFactory, this.connectionFactory.getComponentName())
-				: null;
+				: Collections.emptyMap();
 	}
 
 }

spring-integration-ip/src/main/java/org/springframework/integration/ip/dsl/TcpOutboundChannelAdapterSpec.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 the original author or authors.
+ * Copyright 2016-2023 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.
@@ -56,7 +56,7 @@ public class TcpOutboundChannelAdapterSpec
 	 */
 	protected TcpOutboundChannelAdapterSpec(AbstractConnectionFactorySpec<?, ?> connectionFactorySpec) {
 		this.target = new TcpSendingMessageHandler();
-		this.connectionFactory = connectionFactorySpec.get();
+		this.connectionFactory = connectionFactorySpec.getObject();
 		this.target.setConnectionFactory(this.connectionFactory);
 	}
 
@@ -94,7 +94,7 @@ public class TcpOutboundChannelAdapterSpec
 	public Map<Object, String> getComponentsToRegister() {
 		return this.connectionFactory != null
 				? Collections.singletonMap(this.connectionFactory, this.connectionFactory.getComponentName())
-				: null;
+				: Collections.emptyMap();
 	}
 
 }

spring-integration-ip/src/main/java/org/springframework/integration/ip/dsl/TcpOutboundGatewaySpec.java

@@ -58,7 +58,7 @@ public class TcpOutboundGatewaySpec extends MessageHandlerSpec<TcpOutboundGatewa
 	 */
 	public TcpOutboundGatewaySpec(TcpClientConnectionFactorySpec<?, ?> connectionFactorySpec) {
 		this.target = new TcpOutboundGateway();
-		this.connectionFactory = connectionFactorySpec.get();
+		this.connectionFactory = connectionFactorySpec.getObject();
 		this.target.setConnectionFactory(this.connectionFactory);
 	}
 
@@ -120,8 +120,21 @@ public class TcpOutboundGatewaySpec extends MessageHandlerSpec<TcpOutboundGatewa
 	 * @param channelName the name.
 	 * @return the spec.
 	 * @since 5.4
+	 * @deprecated in favor of {@link #unsolicitedMessageChannelName(String)}
+	 * due to the typo in method name.
 	 */
+	@Deprecated(since = "6.1", forRemoval = true)
 	public TcpOutboundGatewaySpec unsolictedMessageChannelName(String channelName) {
+		return unsolicitedMessageChannelName(channelName);
+	}
+
+	/**
+	 * Set the unsolicited message channel name.
+	 * @param channelName the name.
+	 * @return the spec.
+	 * @since 6.1
+	 */
+	public TcpOutboundGatewaySpec unsolicitedMessageChannelName(String channelName) {
 		this.target.setUnsolicitedMessageChannelName(channelName);
 		return this;
 	}
@@ -131,8 +144,21 @@ public class TcpOutboundGatewaySpec extends MessageHandlerSpec<TcpOutboundGatewa
 	 * @param channel the channel.
 	 * @return the spec.
 	 * @since 5.4
+	 * @deprecated in favor of {@link #unsolicitedMessageChannel(MessageChannel)}
+	 * due to the typo in method name.
 	 */
+	@Deprecated(since = "6.1", forRemoval = true)
 	public TcpOutboundGatewaySpec unsolictedMessageChannelName(MessageChannel channel) {
+		return unsolicitedMessageChannel(channel);
+	}
+
+	/**
+	 * Set the unsolicited message channel.
+	 * @param channel the channel.
+	 * @return the spec.
+	 * @since 6.1
+	 */
+	public TcpOutboundGatewaySpec unsolicitedMessageChannel(MessageChannel channel) {
 		this.target.setUnsolicitedMessageChannel(channel);
 		return this;
 	}
@@ -141,7 +167,7 @@ public class TcpOutboundGatewaySpec extends MessageHandlerSpec<TcpOutboundGatewa
 	public Map<Object, String> getComponentsToRegister() {
 		return this.connectionFactory != null
 				? Collections.singletonMap(this.connectionFactory, this.connectionFactory.getComponentName())
-				: null;
+				: Collections.emptyMap();
 	}
 
 }