Upgrade to Micrometer 1.16.0-M1 and Micrometer Tracing 1.6.0-M1

Closes gh-1269

Author: bclozel

platform/build.gradle

@@ -11,8 +11,8 @@ dependencies {
 	api(platform("com.fasterxml.jackson:jackson-bom:2.18.4"))
 	api(platform("tools.jackson:jackson-bom:3.0.0-rc4"))
 	api(platform("io.projectreactor:reactor-bom:2025.0.0-M5"))
-	api(platform("io.micrometer:micrometer-bom:1.15.0"))
-	api(platform("io.micrometer:micrometer-tracing-bom:1.5.0"))
+	api(platform("io.micrometer:micrometer-bom:1.16.0-M1"))
+	api(platform("io.micrometer:micrometer-tracing-bom:1.6.0-M1"))
 	api(platform("org.springframework.data:spring-data-bom:2025.1.0-M3"))
 	api(platform("org.springframework.security:spring-security-bom:6.5.0"))
 	api(platform("com.querydsl:querydsl-bom:5.1.0"))
@@ -27,7 +27,6 @@ dependencies {
 
 	constraints {
 		api("com.graphql-java:graphql-java:${graphQlJavaVersion}")
-		api("io.micrometer:context-propagation:1.1.3")
 
 		api("jakarta.annotation:jakarta.annotation-api:3.0.0")
 		api("jakarta.servlet:jakarta.servlet-api:6.1.0")

spring-graphql/src/main/java/org/springframework/graphql/observation/GraphQlObservationInstrumentation.java

@@ -202,7 +202,7 @@ public DataFetcher<?> instrumentDataFetcher(DataFetcher<?> dataFetcher,
 							observationContext.setValue(result);
 							if (error != null) {
 								if (error instanceof CompletionException completionException) {
-									dataFetcherObservation.error(error.getCause());
+									dataFetcherObservation.error((error.getCause() != null) ? error.getCause() : error);
 									dataFetcherObservation.stop();
 									throw completionException;
 								}