GH-3194: Add generics to Amqp and Jms channel impls

Fixes https://github.com/spring-projects/spring-integration/issues/3194

For now we keep the hierarchy, but try to generalize channel specs
a bit, so that ones who use `publishSubscribeChannel` can count on
`BroadcastCapableChannel` as interface to utilize.

spring-integration-jms/src/main/java/org/springframework/integration/jms/dsl/Jms.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2019 the original author or authors.
+ * Copyright 2014-2020 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.
@@ -19,6 +19,7 @@ package org.springframework.integration.jms.dsl;
 import javax.jms.ConnectionFactory;
 import javax.jms.Destination;
 
+import org.springframework.integration.jms.PollableJmsChannel;
 import org.springframework.jms.core.JmsTemplate;
 import org.springframework.jms.listener.AbstractMessageListenerContainer;
 import org.springframework.jms.listener.DefaultMessageListenerContainer;
@@ -29,6 +30,7 @@ import org.springframework.lang.Nullable;
  *
  * @author Artem Bilan
  * @author Gary Russell
+ * @author Artem Vozhdayenko
  *
  * @since 5.0
  */
@@ -39,7 +41,7 @@ public final class Jms {
 	 * @param connectionFactory the JMS ConnectionFactory to build on
 	 * @return the {@link JmsPollableMessageChannelSpec} instance
 	 */
-	public static JmsPollableMessageChannelSpec<?> pollableChannel(ConnectionFactory connectionFactory) {
+	public static JmsPollableMessageChannelSpec<?, PollableJmsChannel> pollableChannel(ConnectionFactory connectionFactory) {
 		return pollableChannel(null, connectionFactory);
 	}
 
@@ -49,10 +51,10 @@ public final class Jms {
 	 * @param connectionFactory the JMS ConnectionFactory to build on
 	 * @return the {@link JmsPollableMessageChannelSpec} instance
 	 */
-	public static JmsPollableMessageChannelSpec<?> pollableChannel(@Nullable String id,
+	public static JmsPollableMessageChannelSpec<?, PollableJmsChannel> pollableChannel(@Nullable String id,
 			ConnectionFactory connectionFactory) {
-
-		return new JmsPollableMessageChannelSpec<>(connectionFactory).id(id);
+		JmsPollableMessageChannelSpec<?, PollableJmsChannel> spec = new JmsPollableMessageChannelSpec<>(connectionFactory);
+		return spec.id(id);
 	}
 
 	/**
@@ -60,7 +62,7 @@ public final class Jms {
 	 * @param connectionFactory the JMS ConnectionFactory to build on
 	 * @return the {@link JmsMessageChannelSpec} instance
 	 */
-	public static JmsMessageChannelSpec<?> channel(ConnectionFactory connectionFactory) {
+	public static JmsMessageChannelSpec<?, ?> channel(ConnectionFactory connectionFactory) {
 		return channel(null, connectionFactory);
 	}
 
@@ -70,7 +72,7 @@ public final class Jms {
 	 * @param connectionFactory the JMS ConnectionFactory to build on
 	 * @return the {@link JmsMessageChannelSpec} instance
 	 */
-	public static JmsMessageChannelSpec<?> channel(@Nullable String id, ConnectionFactory connectionFactory) {
+	public static JmsMessageChannelSpec<?, ?> channel(@Nullable String id, ConnectionFactory connectionFactory) {
 		return new JmsMessageChannelSpec<>(connectionFactory)
 				.id(id);
 	}
@@ -180,7 +182,7 @@ public final class Jms {
 	 * @param <C>               the {@link AbstractMessageListenerContainer} inheritor type
 	 * @return the {@link JmsInboundGatewaySpec} instance
 	 */
-	@SuppressWarnings({ "rawtypes", "unchecked" })
+	@SuppressWarnings({"rawtypes", "unchecked"})
 	public static <C extends AbstractMessageListenerContainer>
 	JmsInboundGatewaySpec.JmsInboundGatewayListenerContainerSpec<?, C> inboundGateway(
 			ConnectionFactory connectionFactory, Class<C> containerClass) {
@@ -241,7 +243,7 @@ public final class Jms {
 	 * @param <C>               the {@link AbstractMessageListenerContainer} inheritor type
 	 * @return the {@link JmsMessageDrivenChannelAdapterSpec} instance
 	 */
-	@SuppressWarnings({ "rawtypes", "unchecked" })
+	@SuppressWarnings({"rawtypes", "unchecked"})
 	public static <C extends AbstractMessageListenerContainer>
 	JmsMessageDrivenChannelAdapterSpec.JmsMessageDrivenChannelAdapterListenerContainerSpec<?, C>
 	messageDrivenChannelAdapter(ConnectionFactory connectionFactory, Class<C> containerClass) {

spring-integration-jms/src/main/java/org/springframework/integration/jms/dsl/JmsMessageChannelSpec.java

@@ -20,6 +20,7 @@ import java.util.concurrent.Executor;
 
 import javax.jms.ConnectionFactory;
 
+import org.springframework.integration.jms.AbstractJmsChannel;
 import org.springframework.integration.jms.config.JmsChannelFactoryBean;
 import org.springframework.jms.listener.AbstractMessageListenerContainer;
 import org.springframework.transaction.PlatformTransactionManager;
@@ -33,9 +34,12 @@ import org.springframework.util.ErrorHandler;
  *
  * @author Artem Bilan
  * @author Gary Russell
+ * @author Artem Vozhdayenko
+ *
  * @since 5.0
  */
-public class JmsMessageChannelSpec<S extends JmsMessageChannelSpec<S>> extends JmsPollableMessageChannelSpec<S> {
+public class JmsMessageChannelSpec<S extends JmsMessageChannelSpec<S, T>, T
+		extends AbstractJmsChannel> extends JmsPollableMessageChannelSpec<S, T> {
 
 	protected JmsMessageChannelSpec(ConnectionFactory connectionFactory) {
 		super(new JmsChannelFactoryBean(true), connectionFactory);

spring-integration-jms/src/main/java/org/springframework/integration/jms/dsl/JmsPollableMessageChannelSpec.java

@@ -35,11 +35,12 @@ import org.springframework.lang.Nullable;
  *
  * @author Artem Bilan
  * @author Gary Russell
+ * @author Artem Vozhdayenko
  *
  * @since 5.0
  */
-public class JmsPollableMessageChannelSpec<S extends JmsPollableMessageChannelSpec<S>>
-		extends MessageChannelSpec<S, AbstractJmsChannel> {
+public class JmsPollableMessageChannelSpec<S extends JmsPollableMessageChannelSpec<S, T>, T extends AbstractJmsChannel>
+		extends MessageChannelSpec<S, T> {
 
 	protected final JmsChannelFactoryBean jmsChannelFactoryBean; // NOSONAR - final
 
@@ -218,9 +219,10 @@ public class JmsPollableMessageChannelSpec<S extends JmsPollableMessageChannelSp
 	}
 
 	@Override
-	protected AbstractJmsChannel doGet() {
+	@SuppressWarnings("unchecked")
+	protected T doGet() {
 		try {
-			this.channel = this.jmsChannelFactoryBean.getObject();
+			this.channel = (T) this.jmsChannelFactoryBean.getObject();
 		}
 		catch (Exception e) {
 			throw new BeanCreationException("Cannot create the JMS MessageChannel", e);

spring-integration-jms/src/main/java/org/springframework/integration/jms/dsl/JmsPublishSubscribeMessageChannelSpec.java

@@ -18,15 +18,19 @@ package org.springframework.integration.jms.dsl;
 
 import javax.jms.ConnectionFactory;
 
+import org.springframework.integration.jms.SubscribableJmsChannel;
+
 /**
  * A {@link JmsMessageChannelSpec} for a {@link org.springframework.integration.jms.SubscribableJmsChannel}
  * configured with a topic.
  *
  * @author Artem Bilan
+ * @author Artem Vozhdayenko
+ *
  * @since 5.0
  */
 public class JmsPublishSubscribeMessageChannelSpec
-		extends JmsMessageChannelSpec<JmsPublishSubscribeMessageChannelSpec> {
+		extends JmsMessageChannelSpec<JmsPublishSubscribeMessageChannelSpec, SubscribableJmsChannel> {
 
 	protected JmsPublishSubscribeMessageChannelSpec(ConnectionFactory connectionFactory) {
 		super(connectionFactory);

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

@@ -83,6 +83,7 @@ import org.springframework.transaction.PlatformTransactionManager;
  * @author Artem Bilan
  * @author Gary Russell
  * @author Nasko Vasilev
+ * @author Artem Vozhdayenko
  *
  * @since 5.0
  */
@@ -371,8 +372,7 @@ public class JmsTests extends ActiveMQMultiContextTests {
 
 		@Bean
 		public BroadcastCapableChannel jmsPublishSubscribeChannel() {
-			// TODO reconsider target generic type for channel implementation to return from this kind of specs
-			return (BroadcastCapableChannel) Jms.publishSubscribeChannel(jmsConnectionFactory())
+			return Jms.publishSubscribeChannel(jmsConnectionFactory())
 					.destination("pubsub")
 					.get();
 		}