Update dependencies and add null safety assertions

- Upgrade Kotlin from 2.1.21 to 2.2.0
- Update Hibernate Validation from 8.0.2.Final to 9.0.1.Final
- Bump Micrometer from 1.15.2 to 1.16.0-M1
- Update Micrometer Tracing from 1.5.2 to 1.6.0-M1
- Upgrade Reactor from 2025.0.0-SNAPSHOT to 2025.0.0-M5
- Update Spring Data from 2025.1.0-SNAPSHOT to 2025.1.0-M4
- Upgrade Spring from 7.0.0-SNAPSHOT to 7.0.0-M7
- Add null checks for cause and registry in micrometer components

Signed-off-by: Soby Chacko <[email protected]>

Author: sobychacko

build.gradle

@@ -1,5 +1,5 @@
 buildscript {
-	ext.kotlinVersion = '2.1.21'
+	ext.kotlinVersion = '2.2.0'
 	ext.isCI = System.getenv('GITHUB_ACTION')
 	repositories {
 		gradlePluginPortal()
@@ -54,7 +54,7 @@ ext {
 	assertjVersion = '3.27.3'
 	awaitilityVersion = '4.3.0'
 	hamcrestVersion = '3.0'
-	hibernateValidationVersion = '8.0.2.Final'
+	hibernateValidationVersion = '9.0.1.Final'
 	jacksonBomVersion = '2.19.2'
 	jaywayJsonPathVersion = '2.9.0'
 	junit4Version = '4.13.2'
@@ -63,15 +63,15 @@ ext {
 	kotlinCoroutinesVersion = '1.10.2'
 	log4jVersion = '2.24.3'
 	micrometerDocsVersion = '1.0.4'
-	micrometerVersion = '1.15.2'
-	micrometerTracingVersion = '1.5.2'
+	micrometerVersion = '1.16.0-M1'
+	micrometerTracingVersion = '1.6.0-M1'
 	mockitoVersion = '5.18.0'
-	reactorVersion = '2025.0.0-SNAPSHOT'
+	reactorVersion = '2025.0.0-M5'
 	scalaVersion = '2.13'
 	springBootVersion = '3.5.0' // docs module
-	springDataVersion = '2025.1.0-SNAPSHOT'
+	springDataVersion = '2025.1.0-M4'
 	springRetryVersion = '2.0.12'
-	springVersion = '7.0.0-SNAPSHOT'
+	springVersion = '7.0.0-M7'
 
 	idPrefix = 'kafka'
 

spring-kafka/src/main/java/org/springframework/kafka/listener/adapter/MessagingMessageListenerAdapter.java

@@ -559,6 +559,7 @@ else if (!(result instanceof CompletableFuture<?>)) {
 				}
 				else {
 					Throwable cause = t instanceof CompletionException ? t.getCause() : t;
+					cause = cause == null ? t : cause;
 					observation.error(cause);
 					asyncFailure(request, acknowledgment, consumer, cause, source);
 				}

spring-kafka/src/main/java/org/springframework/kafka/support/micrometer/MicrometerHolder.java

@@ -43,7 +43,8 @@ public final class MicrometerHolder {
 
 	private final Map<String, Timer> meters = new ConcurrentHashMap<>();
 
-	private final @Nullable MeterRegistry registry;
+	@SuppressWarnings("NullAway.Init")
+	private final MeterRegistry registry;
 
 	private final String timerName;
 
@@ -69,13 +70,15 @@ public MicrometerHolder(@Nullable ApplicationContext context, String name,
 		if (context == null) {
 			throw new IllegalStateException("No micrometer registry present");
 		}
+		MeterRegistry meterRegistry;
 		try {
-			this.registry = context.getBeanProvider(MeterRegistry.class).getIfUnique();
+			meterRegistry = context.getBeanProvider(MeterRegistry.class).getIfUnique();
 		}
 		catch (NoUniqueBeanDefinitionException ex) {
 			throw new IllegalStateException(ex);
 		}
-		if (this.registry != null) {
+		if (meterRegistry != null) {
+			this.registry = meterRegistry;
 			this.timerName = timerName;
 			this.timerDesc = timerDesc;
 			this.name = name;