GH-1354 Added version header to Metric Message

Resolves #1354
Resolves #1356

polishing

Author: olegz

spring-cloud-stream-core-docs/src/main/asciidoc/spring-cloud-stream-overview.adoc

@@ -2379,7 +2379,7 @@ java -jar time-source.jar \
     --spring.cloud.stream.metrics.meter-filter=spring.integration.*
 ----
 
-The following example shows data published to the binding destination as a result of the preceding command:
+The following example shows the payload of the data published to the binding destination as a result of the preceding command:
 
 [source,javascript]
 ----
@@ -2425,6 +2425,9 @@ The following example shows data published to the binding destination as a resul
 }
 ----
 
+NOTE: Given that the format of the Metric message has slightly changed after migrating to Micrometer, the published message will also have
+a `STREAM_CLOUD_STREAM_VERSION` header set to `2.x` to help distinguish between Metric messages from the older versions of the Spring Cloud Stream.
+
 == Samples
 
 For Spring Cloud Stream samples, see the https://github.com/spring-cloud/spring-cloud-stream-samples[spring-cloud-stream-samples] repository on GitHub.

spring-cloud-stream/src/main/java/org/springframework/cloud/stream/micrometer/DefaultDestinationPublishingMeterRegistry.java

@@ -57,7 +57,8 @@
 import org.apache.commons.logging.LogFactory;
 
 import org.springframework.context.SmartLifecycle;
-import org.springframework.messaging.support.GenericMessage;
+import org.springframework.messaging.Message;
+import org.springframework.messaging.support.MessageBuilder;
 
 /**
  *
@@ -229,7 +230,8 @@ private static final class MessageChannelPublisher implements Consumer<String> {
 		@Override
 		public void accept(String metricData) {
 			logger.trace(metricData);
-			this.metersPublisherBinding.applicationMetrics().send(new GenericMessage<String>(metricData));
+			Message<String> message = MessageBuilder.withPayload(metricData).setHeader("STREAM_CLOUD_STREAM_VERSION", "2.x").build();
+			this.metersPublisherBinding.applicationMetrics().send(message);
 		}
 	}
 }