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-amqp/src/main/java/org/springframework/integration/amqp/dsl/AmqpInboundChannelAdapterSpec.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2022 the original author or authors.
+ * Copyright 2014-2023 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.
@@ -43,13 +43,13 @@ public abstract class AmqpInboundChannelAdapterSpec
 	protected final MessageListenerContainerSpec<?, C> listenerContainerSpec; // NOSONAR final
 
 	protected AmqpInboundChannelAdapterSpec(MessageListenerContainerSpec<?, C> listenerContainerSpec) {
-		super(new AmqpInboundChannelAdapter(listenerContainerSpec.get()));
+		super(new AmqpInboundChannelAdapter(listenerContainerSpec.getObject()));
 		this.listenerContainerSpec = listenerContainerSpec;
 	}
 
 	@Override
 	public Map<Object, String> getComponentsToRegister() {
-		return Collections.singletonMap(this.listenerContainerSpec.get(), this.listenerContainerSpec.getId());
+		return Collections.singletonMap(this.listenerContainerSpec.getObject(), this.listenerContainerSpec.getId());
 	}
 
 }

spring-integration-amqp/src/main/java/org/springframework/integration/amqp/dsl/AmqpInboundGatewaySpec.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2022 the original author or authors.
+ * Copyright 2014-2023 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.
@@ -43,7 +43,7 @@ public abstract class AmqpInboundGatewaySpec
 	protected final AbstractMessageListenerContainerSpec<?, C> listenerContainerSpec; // NOSONAR final
 
 	protected AmqpInboundGatewaySpec(AbstractMessageListenerContainerSpec<?, C> listenerContainerSpec) {
-		super(new AmqpInboundGateway(listenerContainerSpec.get()));
+		super(new AmqpInboundGateway(listenerContainerSpec.getObject()));
 		this.listenerContainerSpec = listenerContainerSpec;
 	}
 
@@ -53,16 +53,16 @@ public abstract class AmqpInboundGatewaySpec
 	 * @param listenerContainerSpec the {@link AbstractMessageListenerContainerSpec} to use.
 	 * @param amqpTemplate the {@link AmqpTemplate} to use.
 	 */
-	AmqpInboundGatewaySpec(
-			AbstractMessageListenerContainerSpec<?, C> listenerContainerSpec,
+	AmqpInboundGatewaySpec(AbstractMessageListenerContainerSpec<?, C> listenerContainerSpec,
 			AmqpTemplate amqpTemplate) {
-		super(new AmqpInboundGateway(listenerContainerSpec.get(), amqpTemplate));
+
+		super(new AmqpInboundGateway(listenerContainerSpec.getObject(), amqpTemplate));
 		this.listenerContainerSpec = listenerContainerSpec;
 	}
 
 	@Override
 	public Map<Object, String> getComponentsToRegister() {
-		return Collections.singletonMap(this.listenerContainerSpec.get(), this.listenerContainerSpec.getId());
+		return Collections.singletonMap(this.listenerContainerSpec.getObject(), this.listenerContainerSpec.getId());
 	}
 
 }

spring-integration-amqp/src/main/java/org/springframework/integration/amqp/dsl/RabbitStreamMessageHandlerSpec.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2022 the original author or authors.
+ * Copyright 2022-2023 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.
@@ -122,7 +122,7 @@ public class RabbitStreamMessageHandlerSpec
 	 * Set to true to wait for a confirmation.
 	 * @param sync true to wait.
 	 * @return this spec.
-	 * @see #setConfirmTimeout(long)
+	 * @see #confirmTimeout(long)
 	 */
 	public RabbitStreamMessageHandlerSpec sync(boolean sync) {
 		this.target.setSync(sync);

spring-integration-amqp/src/test/java/org/springframework/integration/amqp/dsl/AmqpTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2022 the original author or authors.
+ * Copyright 2014-2023 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.
@@ -50,6 +50,7 @@ import org.springframework.context.Lifecycle;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.integration.amqp.channel.AbstractAmqpChannel;
+import org.springframework.integration.amqp.channel.PollableAmqpChannel;
 import org.springframework.integration.amqp.inbound.AmqpInboundChannelAdapter.BatchMode;
 import org.springframework.integration.amqp.inbound.AmqpInboundGateway;
 import org.springframework.integration.amqp.support.AmqpHeaderMapper;
@@ -472,15 +473,16 @@ public class AmqpTests {
 		}
 
 		@Bean
-		public AbstractAmqpChannel unitChannel(ConnectionFactory rabbitConnectionFactory) {
+		public AmqpPollableMessageChannelSpec<?, PollableAmqpChannel> unitChannel(
+				ConnectionFactory rabbitConnectionFactory) {
+
 			return Amqp.pollableChannel(rabbitConnectionFactory)
 					.queueName("si.dsl.test")
 					.channelTransacted(true)
 					.extractPayload(true)
 					.inboundHeaderMapper(mapperIn())
 					.outboundHeaderMapper(mapperOut())
-					.defaultDeliveryMode(MessageDeliveryMode.NON_PERSISTENT)
-					.get();
+					.defaultDeliveryMode(MessageDeliveryMode.NON_PERSISTENT);
 		}
 
 		@Bean

spring-integration-amqp/src/test/java/org/springframework/integration/amqp/outbound/RabbitStreamMessageHandlerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2021-2022 the original author or authors.
+ * Copyright 2021-2023 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.
@@ -36,6 +36,8 @@ import static org.assertj.core.api.Assertions.assertThat;
 /**
  * @author Gary Russell
  * @author Chris Bono
+ * @author Artem Bilan
+ *
  * @since 6.0
  */
 public class RabbitStreamMessageHandlerTests implements RabbitTestContainer {
@@ -56,7 +58,7 @@ public class RabbitStreamMessageHandlerTests implements RabbitTestContainer {
 
 		RabbitStreamMessageHandler handler = RabbitStream.outboundStreamAdapter(streamTemplate)
 				.sync(true)
-				.get();
+				.getObject();
 
 		handler.handleMessage(MessageBuilder.withPayload("foo")
 				.setHeader("bar", "baz")