Fix some Kafka tests for their individual embedded brokers

* Add `package-info.java` to `kafka.aot` and fix NullAway in the `KafkaRuntimeHints`

Author: artembilan

spring-integration-kafka/src/main/java/org/springframework/integration/kafka/aot/KafkaRuntimeHints.java

@@ -18,6 +18,8 @@
 
 import java.util.stream.Stream;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.aot.hint.ExecutableMode;
 import org.springframework.aot.hint.ReflectionHints;
 import org.springframework.aot.hint.RuntimeHints;
@@ -37,7 +39,7 @@
 class KafkaRuntimeHints implements RuntimeHintsRegistrar {
 
 	@Override
-	public void registerHints(RuntimeHints hints, ClassLoader classLoader) {
+	public void registerHints(RuntimeHints hints, @Nullable ClassLoader classLoader) {
 		ReflectionHints reflectionHints = hints.reflection();
 
 		// Java DSL does not register beans during AOT phase, so @Reflective is not reachable from Pausable

spring-integration-kafka/src/main/java/org/springframework/integration/kafka/aot/package-info.java

@@ -0,0 +1,5 @@
+/**
+ * AOT support classes for Apache Kafka Module.
+ */
+@org.jspecify.annotations.NullMarked
+package org.springframework.integration.kafka.aot;

spring-integration-kafka/src/main/java/org/springframework/integration/kafka/package-info.java

@@ -71,6 +71,7 @@
 import org.springframework.kafka.support.Acknowledgment;
 import org.springframework.kafka.support.DefaultKafkaHeaderMapper;
 import org.springframework.kafka.support.KafkaHeaders;
+import org.springframework.kafka.test.context.EmbeddedKafka;
 import org.springframework.kafka.test.utils.KafkaTestUtils;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageChannel;
@@ -97,6 +98,7 @@
  */
 @SpringJUnitConfig
 @DirtiesContext
+@EmbeddedKafka
 public class KafkaDslTests {
 
 	private static final Log log = LogFactory.getLog(KafkaDslTests.class);
@@ -275,7 +277,7 @@ public static class ContextConfiguration {
 
 		private Object fromSource;
 
-		@Value("${spring.global.embedded.kafka.brokers}")
+		@Value("${spring.kafka.bootstrap-servers}")
 		String embeddedKafkaBrokers;
 
 		@Bean

spring-integration-kafka/src/test/java/org/springframework/integration/kafka/dsl/KafkaDslTests.java

@@ -47,6 +47,7 @@ import org.springframework.kafka.requestreply.ReplyingKafkaTemplate
 import org.springframework.kafka.support.Acknowledgment
 import org.springframework.kafka.support.DefaultKafkaHeaderMapper
 import org.springframework.kafka.support.KafkaHeaders
+import org.springframework.kafka.test.context.EmbeddedKafka
 import org.springframework.kafka.test.utils.KafkaTestUtils
 import org.springframework.messaging.Message
 import org.springframework.messaging.MessageChannel
@@ -71,6 +72,7 @@ import java.util.stream.Stream
 
 @SpringJUnitConfig
 @DirtiesContext
+@EmbeddedKafka
 class KafkaDslKotlinTests {
 
 	companion object {
@@ -205,7 +207,7 @@ class KafkaDslKotlinTests {
 
 		var fromSource: Any? = null
 
-		@Value("\${spring.global.embedded.kafka.brokers}")
+		@Value("\${spring.kafka.bootstrap-servers}")
 		lateinit var embeddedKafkaBrokers: String
 
 		@Bean