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-jms/src/test/java/org/springframework/integration/jms/dsl/JmsTests.java

@@ -36,7 +36,6 @@ import org.springframework.integration.annotation.InboundChannelAdapter;
 import org.springframework.integration.annotation.IntegrationComponentScan;
 import org.springframework.integration.annotation.MessagingGateway;
 import org.springframework.integration.annotation.Poller;
-import org.springframework.integration.channel.BroadcastCapableChannel;
 import org.springframework.integration.channel.DirectChannel;
 import org.springframework.integration.channel.FixedSubscriberChannel;
 import org.springframework.integration.channel.QueueChannel;
@@ -46,11 +45,14 @@ import org.springframework.integration.core.MessageSource;
 import org.springframework.integration.dsl.IntegrationFlow;
 import org.springframework.integration.dsl.IntegrationFlowDefinition;
 import org.springframework.integration.dsl.MessageChannels;
+import org.springframework.integration.dsl.PollerSpec;
 import org.springframework.integration.dsl.Pollers;
+import org.springframework.integration.dsl.QueueChannelSpec;
 import org.springframework.integration.endpoint.MethodInvokingMessageSource;
 import org.springframework.integration.handler.AbstractReplyProducingMessageHandler;
 import org.springframework.integration.jms.ActiveMQMultiContextTests;
 import org.springframework.integration.jms.JmsDestinationPollingSource;
+import org.springframework.integration.jms.SubscribableJmsChannel;
 import org.springframework.integration.scheduling.PollerMetadata;
 import org.springframework.integration.support.MessageBuilder;
 import org.springframework.integration.test.util.TestUtils;
@@ -302,8 +304,8 @@ public class JmsTests extends ActiveMQMultiContextTests {
 		}
 
 		@Bean(name = PollerMetadata.DEFAULT_POLLER)
-		public PollerMetadata poller() {
-			return Pollers.fixedDelay(1000).get();
+		public PollerSpec poller() {
+			return Pollers.fixedDelay(1000);
 		}
 
 		@Bean
@@ -338,30 +340,29 @@ public class JmsTests extends ActiveMQMultiContextTests {
 		}
 
 		@Bean
-		public MessageChannel jmsOutboundInboundReplyChannel() {
-			return MessageChannels.queue().get();
+		public QueueChannelSpec jmsOutboundInboundReplyChannel() {
+			return MessageChannels.queue();
 		}
 
 		@Bean
-		public IntegrationFlow jmsInboundFlow() {
+		public IntegrationFlow jmsInboundFlow(QueueChannel jmsOutboundInboundReplyChannel) {
 			return IntegrationFlow
 					.from(Jms.inboundAdapter(amqFactory).destination("jmsInbound"))
 					.<String, String>transform(String::toUpperCase)
-					.channel(this.jmsOutboundInboundReplyChannel())
+					.channel(jmsOutboundInboundReplyChannel)
 					.get();
 		}
 
 		@Bean
-		public BroadcastCapableChannel jmsPublishSubscribeChannel() {
+		public JmsPublishSubscribeMessageChannelSpec jmsPublishSubscribeChannel() {
 			return Jms.publishSubscribeChannel(amqFactory)
-					.destination("pubsub")
-					.get();
+					.destination("pubsub");
 		}
 
 		@Bean
-		public IntegrationFlow pubSubFlow() {
+		public IntegrationFlow pubSubFlow(SubscribableJmsChannel jmsPublishSubscribeChannel) {
 			return f -> f
-					.publishSubscribeChannel(jmsPublishSubscribeChannel(),
+					.publishSubscribeChannel(jmsPublishSubscribeChannel,
 							pubsub -> pubsub
 									.subscribe(subFlow -> subFlow
 											.channel(c -> c.queue("jmsPubSubBridgeChannel")))
@@ -408,8 +409,7 @@ public class JmsTests extends ActiveMQMultiContextTests {
 					.from(Jms.messageDrivenChannelAdapter(
 							Jms.container(amqFactory, "containerSpecDestination")
 									.pubSubDomain(false)
-									.taskExecutor(Executors.newCachedThreadPool())
-									.get()))
+									.taskExecutor(Executors.newCachedThreadPool())))
 					.transform(String::trim)
 					.channel(jmsOutboundInboundReplyChannel())
 					.get();

spring-integration-jms/src/test/kotlin/org/springframework/integration/jms/dsl/JmsDslKotlinTests.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-2021 the original author or authors.
+ * Copyright 2018-2023 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.
@@ -29,6 +29,7 @@ import org.springframework.beans.factory.annotation.Qualifier
 import org.springframework.context.annotation.Bean
 import org.springframework.context.annotation.Configuration
 import org.springframework.integration.IntegrationMessageHeaderAccessor
+import org.springframework.integration.channel.QueueChannel
 import org.springframework.integration.config.EnableIntegration
 import org.springframework.integration.dsl.MessageChannels
 import org.springframework.integration.dsl.integrationFlow
@@ -112,10 +113,10 @@ class JmsDslKotlinTests : ActiveMQMultiContextTests() {
 		}
 
 		@Bean
-		fun jmsOutboundInboundReplyChannel() = MessageChannels.queue().get()
+		fun jmsOutboundInboundReplyChannel() = MessageChannels.queue()
 
 		@Bean
-		fun jmsMessageDrivenFlowWithContainer() =
+		fun jmsMessageDrivenFlowWithContainer(jmsOutboundInboundReplyChannel: QueueChannel) =
 			integrationFlow(
 				Jms.messageDrivenChannelAdapter(
 					Jms.container(amqFactory, "containerSpecDestination")
@@ -125,7 +126,7 @@ class JmsDslKotlinTests : ActiveMQMultiContextTests() {
 					.headerMapper(jmsHeaderMapper())
 			) {
 				transform { it: String -> it.trim { it <= ' ' } }
-				channel(jmsOutboundInboundReplyChannel())
+				channel(jmsOutboundInboundReplyChannel)
 			}
 
 	}