Use @EnableModule(Channels.class) instead of field declarations

Standard channel interface types of Sink, Source, Processor
are provided, but user can create others with @Input and
@Output MessageChannel methods.

To get the declared channels in an app you can use the
@ModuleChannels qualifier to inject the interface, e.g.
@ModuleChannels(Cafe.class) injects the channels defined
in the Cafe.

spring-cloud-stream-samples/double/src/main/java/config/SinkModuleDefinition.java

@@ -18,25 +18,20 @@ package config;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
-
 import org.springframework.cloud.stream.annotation.EnableModule;
-import org.springframework.cloud.stream.annotation.Input;
+import org.springframework.cloud.stream.annotation.Sink;
 import org.springframework.integration.annotation.ServiceActivator;
-import org.springframework.messaging.MessageChannel;
 
 /**
  * @author Dave Syer
  * @author Marius Bogoevici
  */
-@EnableModule
+@EnableModule(Sink.class)
 public class SinkModuleDefinition {
 
 	private static Logger logger = LoggerFactory.getLogger(SinkModuleDefinition.class);
 
-	@Input
-	public MessageChannel input;
-
-	@ServiceActivator(inputChannel="input")
+	@ServiceActivator(inputChannel=Sink.INPUT)
 	public void loggerSink(Object payload) {
 		logger.info("Received: " + payload);
 	}

spring-cloud-stream-samples/double/src/main/java/config/SourceModuleDefinition.java

@@ -21,29 +21,25 @@ import java.util.Date;
 
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.cloud.stream.annotation.EnableModule;
-import org.springframework.cloud.stream.annotation.Output;
+import org.springframework.cloud.stream.annotation.Source;
 import org.springframework.context.annotation.Bean;
 import org.springframework.integration.annotation.InboundChannelAdapter;
 import org.springframework.integration.annotation.Poller;
 import org.springframework.integration.core.MessageSource;
-import org.springframework.messaging.MessageChannel;
 import org.springframework.messaging.support.GenericMessage;
 
 /**
  * @author Dave Syer
  * @author Marius Bogoevici
  */
-@EnableModule
+@EnableModule(Source.class)
 public class SourceModuleDefinition {
 
 	@Value("${format:YYYY/MM/dd hh:mm:ss}")
 	private String format;
 
-	@Output
-	public MessageChannel output;
-
 	@Bean
-	@InboundChannelAdapter(value = "output", autoStartup = "false", poller = @Poller(fixedDelay = "${fixedDelay}", maxMessagesPerPoll = "1"))
+	@InboundChannelAdapter(value = Source.OUTPUT, autoStartup = "false", poller = @Poller(fixedDelay = "${fixedDelay}", maxMessagesPerPoll = "1"))
 	public MessageSource<String> timerMessageSource() {
 		return () -> new GenericMessage<>(new SimpleDateFormat(this.format).format(new Date()));
 	}