KafkaBinderConfigurationProperties metadata

When generating configuration metadata (spring-configuration-metadata.json),
KafkaBinderConfigurationProperties class is missing all the information except
for the constructor bound KafkaProperties. We need to add the @Autowired on the
constructor so that Boot will not do a constructor binding and thus include all
the JavaBeans style properties in the metadata. See this Boot issue for more details.

https://github.com/spring-projects/spring-boot/issues/34031

In addition, this @Autowired is necessary for the properties to be correctly
bound when running in native mode.

Resolves https://github.com/spring-cloud/spring-cloud-stream/issues/2640
Resolves https://github.com/spring-cloud/spring-cloud-stream/issues/2644

binders/kafka-binder/spring-cloud-stream-binder-kafka-core/src/main/java/org/springframework/cloud/stream/binder/kafka/properties/KafkaBinderConfigurationProperties.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2022 the original author or authors.
+ * Copyright 2015-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -36,6 +36,7 @@ import org.apache.commons.logging.LogFactory;
 import org.apache.kafka.clients.consumer.ConsumerConfig;
 import org.apache.kafka.clients.producer.ProducerConfig;
 
+import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.autoconfigure.kafka.KafkaProperties;
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.cloud.stream.binder.HeaderMode;
@@ -144,6 +145,20 @@ public class KafkaBinderConfigurationProperties {
 	 */
 	private boolean enableObservation;
 
+	/**
+	 * @Autowired on this constructor is necessary in order to make sure that all the optional (provided as JavaBean setters)
+	 * properties in this class are taken into consideration when generating configuration metadata.
+	 * In addition, in order for all the properties to be discovered and bound when running as a native
+	 * application, this @Autowired is necessary, so that Boot binding mechanism considers all the properties.
+	 * See the following issues for more details.
+	 *
+	 * https://github.com/spring-cloud/spring-cloud-stream/issues/2640
+	 * https://github.com/spring-projects/spring-boot/issues/34031
+	 * https://github.com/spring-cloud/spring-cloud-stream/issues/2644
+	 *
+	 * @param kafkaProperties Spring Kafka properties autoconfigured by Spring Boot
+	 */
+	@Autowired
 	public KafkaBinderConfigurationProperties(KafkaProperties kafkaProperties) {
 		Assert.notNull(kafkaProperties, "'kafkaProperties' cannot be null");
 		this.kafkaProperties = kafkaProperties;

samples/kafka-binder-native-app/pom.xml

@@ -72,4 +72,69 @@
 		</plugins>
 	</build>
 
+	<repositories>
+		<repository>
+			<id>spring-snapshots</id>
+			<name>Spring Snapshots</name>
+			<url>https://repo.spring.io/libs-snapshot-local</url>
+			<snapshots>
+				<enabled>true</enabled>
+			</snapshots>
+			<releases>
+				<enabled>false</enabled>
+			</releases>
+		</repository>
+		<repository>
+			<id>spring-milestones</id>
+			<name>Spring Milestones</name>
+			<url>https://repo.spring.io/libs-milestone-local</url>
+			<snapshots>
+				<enabled>false</enabled>
+			</snapshots>
+		</repository>
+		<repository>
+			<id>spring-releases</id>
+			<name>Spring Releases</name>
+			<url>https://repo.spring.io/release</url>
+			<snapshots>
+				<enabled>false</enabled>
+			</snapshots>
+		</repository>
+		<repository>
+			<id>confluent</id>
+			<url>https://packages.confluent.io/maven/</url>
+		</repository>
+	</repositories>
+
+	<pluginRepositories>
+		<pluginRepository>
+			<id>spring-snapshots</id>
+			<name>Spring Snapshots</name>
+			<url>https://repo.spring.io/libs-snapshot-local</url>
+			<snapshots>
+				<enabled>true</enabled>
+			</snapshots>
+			<releases>
+				<enabled>false</enabled>
+			</releases>
+		</pluginRepository>
+		<pluginRepository>
+			<id>spring-milestones</id>
+			<name>Spring Milestones</name>
+			<url>https://repo.spring.io/libs-milestone-local</url>
+			<snapshots>
+				<enabled>false</enabled>
+			</snapshots>
+		</pluginRepository>
+		<pluginRepository>
+			<id>spring-releases</id>
+			<name>Spring Releases</name>
+			<url>https://repo.spring.io/libs-release-local</url>
+			<snapshots>
+				<enabled>false</enabled>
+			</snapshots>
+		</pluginRepository>
+	</pluginRepositories>
+
+
 </project>

samples/kafka-binder-native-app/src/main/resources/application.yml

@@ -7,6 +7,6 @@ spring.cloud:
         destination: graalUppercaseFunction-in-0
       graalLoggingConsumer-in-0:
         destination: graalUppercaseFunction-out-0
-spring:
-  kafka:
-    bootstrap-servers: localhost:9092
+    kafka:
+      binder:
+        brokers: localhost:9092