Align the context propagation entries with the rest of the portfolio.

Closes spring-projects#4218

Author: marcingrzejszczak

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/observability/ContextProviderFactory.java

@@ -85,7 +85,8 @@ public RequestContext getContext() {
 
 			Observation currentObservation = observationRegistry.getCurrentObservation();
 			if (currentObservation != null) {
-				requestContext.put(Observation.class, currentObservation);
+				// Aligned with ObservationThreadLocalAccessor.KEY
+				requestContext.put("micrometer.observation", currentObservation);
 			}
 
 			return requestContext;

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/observability/MongoObservationCommandListener.java

@@ -42,6 +42,11 @@ public class MongoObservationCommandListener implements CommandListener {
 
 	private static final Log log = LogFactory.getLog(MongoObservationCommandListener.class);
 
+	/**
+	 * Aligns with ObservationThreadLocalAccessor.KEY.
+	 */
+	private static final String MICROMETER_OBSERVATION_KEY = "micrometer.observation";
+
 	private final ObservationRegistry observationRegistry;
 	private final @Nullable ConnectionString connectionString;
 
@@ -114,8 +119,7 @@ public void commandStarted(CommandStartedEvent event) {
 
 		observation.start();
 
-		requestContext.put(Observation.class, observation);
-		requestContext.put(MongoHandlerContext.class, observationContext);
+		requestContext.put(MICROMETER_OBSERVATION_KEY, observation);
 
 		if (log.isDebugEnabled()) {
 			log.debug(
@@ -132,12 +136,12 @@ public void commandSucceeded(CommandSucceededEvent event) {
 			return;
 		}
 
-		Observation observation = requestContext.getOrDefault(Observation.class, null);
+		Observation observation = requestContext.getOrDefault(MICROMETER_OBSERVATION_KEY, null);
 		if (observation == null) {
 			return;
 		}
 
-		MongoHandlerContext context = requestContext.get(MongoHandlerContext.class);
+		MongoHandlerContext context = (MongoHandlerContext) observation.getContext();
 		context.setCommandSucceededEvent(event);
 
 		if (log.isDebugEnabled()) {
@@ -156,12 +160,12 @@ public void commandFailed(CommandFailedEvent event) {
 			return;
 		}
 
-		Observation observation = requestContext.getOrDefault(Observation.class, null);
+		Observation observation = requestContext.getOrDefault(MICROMETER_OBSERVATION_KEY, null);
 		if (observation == null) {
 			return;
 		}
 
-		MongoHandlerContext context = requestContext.get(MongoHandlerContext.class);
+		MongoHandlerContext context = (MongoHandlerContext) observation.getContext();
 		context.setCommandFailedEvent(event);
 
 		if (log.isDebugEnabled()) {
@@ -181,7 +185,7 @@ public void commandFailed(CommandFailedEvent event) {
 	@Nullable
 	private static Observation observationFromContext(RequestContext context) {
 
-		Observation observation = context.getOrDefault(Observation.class, null);
+		Observation observation = context.getOrDefault(MICROMETER_OBSERVATION_KEY, null);
 
 		if (observation != null) {
 
@@ -192,7 +196,7 @@ private static Observation observationFromContext(RequestContext context) {
 		}
 
 		if (log.isDebugEnabled()) {
-			log.debug("No observation was found - will not create any child spans");
+			log.debug("No observation was found - will not create any child observations");
 		}
 
 		return null;

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/observability/ReactiveIntegrationTests.java

@@ -73,7 +73,7 @@ public SampleTestRunnerConsumer yourCode() {
 					.verifyComplete();
 
 			repository.findByLastname("Matthews") //
-					.contextWrite(Context.of(Observation.class, intermediate)) //
+					.contextWrite(Context.of("micrometer.observation", intermediate)) //
 					.as(StepVerifier::create).assertNext(actual -> {
 
 						assertThat(actual).extracting("firstname", "lastname").containsExactly("Dave", "Matthews");