GH-3623: Deprecarte an IntegrationFlows

Fixes #3623

* `IntegrationFlow` refactoring
* Apply several code style improvements and good practices
* Code style: no empty lines for methods javadocs
* make deprecated implementation reuse actual one instead of the copy-paste approach
* add whats-new comments
* Fix whats-new page according to standards

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2020 the original author or authors.
+ * Copyright 2014-2022 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.
@@ -59,7 +59,6 @@
 import org.springframework.integration.config.EnableIntegration;
 import org.springframework.integration.dsl.IntegrationFlow;
 import org.springframework.integration.dsl.IntegrationFlowBuilder;
-import org.springframework.integration.dsl.IntegrationFlows;
 import org.springframework.integration.dsl.Transformers;
 import org.springframework.integration.dsl.context.IntegrationFlowContext;
 import org.springframework.integration.support.MessageBuilder;
@@ -161,7 +160,7 @@ public void testAmqpOutboundFlow() {
 
 	@Test
 	public void testTemplateChannelTransacted() {
-		IntegrationFlowBuilder flow = IntegrationFlows.from(Amqp.channel("testTemplateChannelTransacted",
+		IntegrationFlowBuilder flow = IntegrationFlow.from(Amqp.channel("testTemplateChannelTransacted",
 				this.rabbitConnectionFactory)
 				.autoStartup(false)
 				.templateChannelTransacted(true));
@@ -235,7 +234,7 @@ void unitTestChannel() {
 	@Test
 	void testContentTypeOverrideWithReplyHeadersMappedLast() {
 		IntegrationFlow testFlow =
-				IntegrationFlows
+				IntegrationFlow
 						.from(Amqp.inboundGateway(this.rabbitConnectionFactory, this.amqpQueue2)
 								.replyHeadersMappedLast(true))
 						.transform(Transformers.fromJson())
@@ -300,7 +299,7 @@ public Queue defaultReplyTo() {
 
 		@Bean
 		public IntegrationFlow amqpFlow(ConnectionFactory rabbitConnectionFactory, AmqpTemplate amqpTemplate) {
-			return IntegrationFlows
+			return IntegrationFlow
 					.from(Amqp.inboundGateway(rabbitConnectionFactory, amqpTemplate, queue())
 							.id("amqpInboundGateway")
 							.configureContainer(c -> c
@@ -315,7 +314,7 @@ public IntegrationFlow amqpFlow(ConnectionFactory rabbitConnectionFactory, AmqpT
 
 		// syntax only
 		public IntegrationFlow amqpDMLCFlow(ConnectionFactory rabbitConnectionFactory, AmqpTemplate amqpTemplate) {
-			return IntegrationFlows
+			return IntegrationFlow
 					.from(Amqp.inboundGateway(new DirectMessageListenerContainer())
 							.id("amqpInboundGateway")
 							.configureContainer(c -> c
@@ -329,7 +328,7 @@ public IntegrationFlow amqpDMLCFlow(ConnectionFactory rabbitConnectionFactory, A
 
 		@Bean
 		public IntegrationFlow amqpOutboundFlow(ConnectionFactory rabbitConnectionFactory, AmqpTemplate amqpTemplate) {
-			return IntegrationFlows.from(Amqp.channel("amqpOutboundInput", rabbitConnectionFactory))
+			return IntegrationFlow.from(Amqp.channel("amqpOutboundInput", rabbitConnectionFactory))
 					.handle(Amqp.outboundAdapter(amqpTemplate).routingKeyExpression("headers.routingKey"))
 					.get();
 		}
@@ -346,7 +345,7 @@ public Queue amqpReplyChannel() {
 
 		@Bean
 		public IntegrationFlow amqpInboundFlow(ConnectionFactory rabbitConnectionFactory) {
-			return IntegrationFlows.from(Amqp.inboundAdapter(rabbitConnectionFactory, fooQueue())
+			return IntegrationFlow.from(Amqp.inboundAdapter(rabbitConnectionFactory, fooQueue())
 						.configureContainer(container -> container.consumerBatchEnabled(true)
 								.batchSize(2))
 						.batchMode(BatchMode.EXTRACT_PAYLOADS)
@@ -384,7 +383,7 @@ public Queue exDLQ() {
 
 		@Bean
 		public IntegrationFlow inboundWithExceptionFlow(ConnectionFactory cf) {
-			return IntegrationFlows.from(Amqp.inboundAdapter(cf, exQueue())
+			return IntegrationFlow.from(Amqp.inboundAdapter(cf, exQueue())
 					.configureContainer(c -> c.defaultRequeueRejected(false))
 					.errorChannel("errors.input"))
 					.handle(m -> {
@@ -421,7 +420,7 @@ public Queue exConvDLQ() {
 
 		@Bean
 		public IntegrationFlow inboundWithConvExceptionFlow(ConnectionFactory cf) {
-			return IntegrationFlows.from(Amqp.inboundAdapter(cf, exConvQueue())
+			return IntegrationFlow.from(Amqp.inboundAdapter(cf, exConvQueue())
 					.configureContainer(c -> c.defaultRequeueRejected(false))
 					.messageConverter(new SimpleMessageConverter() {
 

spring-integration-amqp/src/test/java/org/springframework/integration/amqp/inbound/AmqpMessageSourceIntegrationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-2019 the original author or authors.
+ * Copyright 2018-2022 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.
@@ -54,7 +54,6 @@
 import org.springframework.integration.config.EnableIntegration;
 import org.springframework.integration.core.MessageSource;
 import org.springframework.integration.dsl.IntegrationFlow;
-import org.springframework.integration.dsl.IntegrationFlows;
 import org.springframework.integration.dsl.Pollers;
 import org.springframework.integration.support.AbstractIntegrationMessageBuilder;
 import org.springframework.messaging.handler.annotation.Header;
@@ -198,7 +197,7 @@ public void ack(@Header(IntegrationMessageHeaderAccessor.ACKNOWLEDGMENT_CALLBACK
 
 		@Bean
 		public IntegrationFlow flow() {
-			return IntegrationFlows.from(Amqp.inboundPolledAdapter(connectionFactory(), DSL_QUEUE),
+			return IntegrationFlow.from(Amqp.inboundPolledAdapter(connectionFactory(), DSL_QUEUE),
 							e -> e.poller(Pollers.fixedDelay(100)).autoStartup(false))
 					.handle(p -> {
 						this.fromDsl = p.getPayload();
@@ -209,7 +208,7 @@ public IntegrationFlow flow() {
 
 		@Bean
 		public IntegrationFlow messageSourceChannelFlow() {
-			return IntegrationFlows.from(interceptedSource(),
+			return IntegrationFlow.from(interceptedSource(),
 							e -> e.poller(Pollers.fixedDelay(100)).autoStartup(false))
 					.handle(p -> {
 						this.fromInterceptedSource = p.getPayload();

spring-integration-amqp/src/test/java/org/springframework/integration/amqp/support/BoundRabbitChannelAdviceIntegrationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-2019 the original author or authors.
+ * Copyright 2018-2022 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.
@@ -41,7 +41,6 @@
 import org.springframework.integration.amqp.dsl.Amqp;
 import org.springframework.integration.config.EnableIntegration;
 import org.springframework.integration.dsl.IntegrationFlow;
-import org.springframework.integration.dsl.IntegrationFlows;
 import org.springframework.integration.test.util.TestUtils;
 import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
 
@@ -108,7 +107,7 @@ public BoundRabbitChannelAdvice advice(RabbitTemplate template) {
 
 		@Bean
 		public IntegrationFlow flow(RabbitTemplate template, BoundRabbitChannelAdvice advice) {
-			return IntegrationFlows.from(Gate.class)
+			return IntegrationFlow.from(Gate.class)
 					.split(s -> s.delimiters(",")
 							.advice(advice))
 					.<String, String>transform(String::toUpperCase)
@@ -118,7 +117,7 @@ public IntegrationFlow flow(RabbitTemplate template, BoundRabbitChannelAdvice ad
 
 		@Bean
 		public IntegrationFlow listener(CachingConnectionFactory ccf) {
-			return IntegrationFlows.from(Amqp.inboundAdapter(ccf, QUEUE))
+			return IntegrationFlow.from(Amqp.inboundAdapter(ccf, QUEUE))
 					.handle(m -> {
 						received.add((String) m.getPayload());
 						this.latch.countDown();

spring-integration-amqp/src/test/java/org/springframework/integration/amqp/support/BoundRabbitChannelAdviceTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-2019 the original author or authors.
+ * Copyright 2018-2022 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 +43,6 @@
 import org.springframework.integration.amqp.dsl.Amqp;
 import org.springframework.integration.config.EnableIntegration;
 import org.springframework.integration.dsl.IntegrationFlow;
-import org.springframework.integration.dsl.IntegrationFlows;
 import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
 
 import com.rabbitmq.client.Channel;
@@ -121,7 +120,7 @@ public RabbitTemplate template() throws Exception {
 
 		@Bean
 		public IntegrationFlow flow(RabbitTemplate template) {
-			return IntegrationFlows.from(Gate.class)
+			return IntegrationFlow.from(Gate.class)
 					.split(s -> s.delimiters(",")
 							.advice(new BoundRabbitChannelAdvice(template, Duration.ofSeconds(10))))
 					.<String, String>transform(String::toUpperCase)

spring-integration-core/src/main/java/org/springframework/integration/dsl/BaseIntegrationFlowDefinition.java

@@ -426,7 +426,7 @@ protected MessageChannel obtainInputChannelFromFlow(IntegrationFlow flow) {
 		MessageChannel messageChannel = flow.getInputChannel();
 		if (messageChannel == null) {
 			messageChannel = new DirectChannel();
-			IntegrationFlowDefinition<?> flowBuilder = IntegrationFlows.from(messageChannel);
+			IntegrationFlowDefinition<?> flowBuilder = IntegrationFlow.from(messageChannel);
 			flow.configure(flowBuilder);
 			addComponent(flowBuilder.get());
 		}
@@ -457,7 +457,7 @@ protected MessageChannel obtainInputChannelFromFlow(IntegrationFlow flow) {
 	 */
 	public B wireTap(String wireTapChannel, Consumer<WireTapSpec> wireTapConfigurer) {
 		DirectChannel internalWireTapChannel = new DirectChannel();
-		addComponent(IntegrationFlows.from(internalWireTapChannel).channel(wireTapChannel).get());
+		addComponent(IntegrationFlow.from(internalWireTapChannel).channel(wireTapChannel).get());
 		return wireTap(internalWireTapChannel, wireTapConfigurer);
 	}
 

spring-integration-core/src/main/java/org/springframework/integration/dsl/BroadcastPublishSubscribeSpec.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2020 the original author or authors.
+ * Copyright 2020-2022 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.
@@ -58,7 +58,7 @@ public BroadcastPublishSubscribeSpec subscribe(IntegrationFlow subFlow) {
 		Assert.notNull(subFlow, "'subFlow' must not be null");
 
 		IntegrationFlowBuilder flowBuilder =
-				IntegrationFlows.from(this.target)
+				IntegrationFlow.from(this.target)
 						.bridge(consumer -> consumer.order(this.order++));
 
 		MessageChannel subFlowInput = subFlow.getInputChannel();

spring-integration-core/src/main/java/org/springframework/integration/dsl/EndpointSpec.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2021 the original author or authors.
+ * Copyright 2016-2022 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.
@@ -163,7 +163,7 @@ protected MessageChannel obtainInputChannelFromFlow(IntegrationFlow subFlow, boo
 		MessageChannel messageChannel = subFlow.getInputChannel();
 		if (messageChannel == null) {
 			messageChannel = new DirectChannel();
-			IntegrationFlowDefinition<?> flowBuilder = IntegrationFlows.from(messageChannel);
+			IntegrationFlowDefinition<?> flowBuilder = IntegrationFlow.from(messageChannel);
 			subFlow.configure(flowBuilder);
 			this.componentsToRegister.put(evaluateInternalBuilder ? flowBuilder.get() : flowBuilder, null);
 		}