Add Nullability support into Java DSL

spring-integration-kafka/src/main/java/org/springframework/integration/kafka/dsl/AbstractKafkaChannelSpec.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2020 the original author or authors.
+ * Copyright 2020-2023 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.
@@ -18,6 +18,7 @@ package org.springframework.integration.kafka.dsl;
 
 import org.springframework.integration.dsl.MessageChannelSpec;
 import org.springframework.integration.kafka.channel.AbstractKafkaChannel;
+import org.springframework.lang.Nullable;
 
 /**
  *
@@ -34,10 +35,11 @@ import org.springframework.integration.kafka.channel.AbstractKafkaChannel;
 public abstract class AbstractKafkaChannelSpec<S extends AbstractKafkaChannelSpec<S, C>, C extends AbstractKafkaChannel>
 		extends MessageChannelSpec<S, C> {
 
+	@Nullable
 	protected String groupId; // NOSONAR
 
 	@Override
-	public S id(String idToSet) { // NOSONAR - increase visibility
+	public S id(@Nullable String idToSet) { // NOSONAR - increase visibility
 		return super.id(idToSet);
 	}
 

spring-integration-kafka/src/main/java/org/springframework/integration/kafka/dsl/KafkaInboundChannelAdapterSpec.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-2020 the original author or authors.
+ * Copyright 2018-2023 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.
@@ -48,6 +48,7 @@ public class KafkaInboundChannelAdapterSpec<K, V>
 	 */
 	KafkaInboundChannelAdapterSpec(ConsumerFactory<K, V> consumerFactory,
 			ConsumerProperties consumerProperties, boolean allowMultiFetch) {
+
 		this.target = new KafkaMessageSource<>(consumerFactory, consumerProperties, allowMultiFetch);
 	}
 

spring-integration-kafka/src/main/java/org/springframework/integration/kafka/dsl/KafkaInboundGatewaySpec.java

@@ -17,6 +17,7 @@
 package org.springframework.integration.kafka.dsl;
 
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.Map;
 import java.util.function.BiConsumer;
 import java.util.function.Consumer;
@@ -26,7 +27,6 @@ import org.apache.kafka.common.TopicPartition;
 import org.springframework.integration.dsl.ComponentsRegistration;
 import org.springframework.integration.dsl.MessagingGatewaySpec;
 import org.springframework.integration.kafka.inbound.KafkaInboundGateway;
-import org.springframework.integration.support.ObjectStringMapBuilder;
 import org.springframework.kafka.core.KafkaTemplate;
 import org.springframework.kafka.listener.AbstractMessageListenerContainer;
 import org.springframework.kafka.listener.ConsumerSeekAware;
@@ -164,10 +164,10 @@ public class KafkaInboundGatewaySpec<K, V, R, S extends KafkaInboundGatewaySpec<
 
 		@Override
 		public Map<Object, String> getComponentsToRegister() {
-			return new ObjectStringMapBuilder()
-					.put(this.containerSpec.getObject(), this.containerSpec.getId())
-					.put(this.templateSpec.getObject(), this.templateSpec.getId())
-					.get();
+			Map<Object, String> components = new HashMap<>();
+			components.put(this.containerSpec.getObject(), this.containerSpec.getId());
+			components.put(this.templateSpec.getObject(), this.templateSpec.getId());
+			return components;
 		}
 
 	}

spring-integration-kafka/src/main/java/org/springframework/integration/kafka/dsl/KafkaMessageDrivenChannelAdapterSpec.java

@@ -141,7 +141,7 @@ public class KafkaMessageDrivenChannelAdapterSpec<K, V, S extends KafkaMessageDr
 	}
 
 	/**
-	 * When using a type-aware message converter (such as {@code StringJsonMessageConverter},
+	 * When using a type-aware message converter (such as {@code StringJsonMessageConverter}),
 	 * set the payload type the converter should create. Defaults to {@link Object}.
 	 * @param payloadType the type.
 	 * @return the spec

spring-integration-kafka/src/main/java/org/springframework/integration/kafka/dsl/KafkaMessageListenerContainerSpec.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-2022 the original author or authors.
+ * Copyright 2018-2023 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.
@@ -28,6 +28,7 @@ import org.springframework.kafka.listener.CommonErrorHandler;
 import org.springframework.kafka.listener.ConcurrentMessageListenerContainer;
 import org.springframework.kafka.listener.ContainerProperties;
 import org.springframework.kafka.support.TopicPartitionOffset;
+import org.springframework.lang.Nullable;
 
 /**
  * A helper class in the Builder pattern style to delegate options to the
@@ -65,7 +66,7 @@ public class KafkaMessageListenerContainerSpec<K, V>
 	}
 
 	@Override
-	public KafkaMessageListenerContainerSpec<K, V> id(String id) { // NOSONAR - increase visibility
+	public KafkaMessageListenerContainerSpec<K, V> id(@Nullable String id) { // NOSONAR - increase visibility
 		return super.id(id);
 	}
 
@@ -205,8 +206,8 @@ public class KafkaMessageListenerContainerSpec<K, V>
 	/**
 	 * Set whether to call consumer.commitSync() or commitAsync() when the
 	 * container is responsible for commits. Default true. See
-	 * https://github.com/spring-projects/spring-kafka/issues/62 At the time of
-	 * writing, async commits are not entirely reliable.
+	 * <a href="https://github.com/spring-projects/spring-kafka/issues/62"/>.
+	 * At the time of writing, async commits are not entirely reliable.
 	 * @param syncCommits true to use commitSync().
 	 * @return the spec.
 	 * @see ContainerProperties#setSyncCommits(boolean)

spring-integration-kafka/src/main/java/org/springframework/integration/kafka/dsl/KafkaTemplateSpec.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-2020 the original author or authors.
+ * Copyright 2018-2023 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.
@@ -21,6 +21,7 @@ import org.springframework.kafka.core.KafkaTemplate;
 import org.springframework.kafka.core.ProducerFactory;
 import org.springframework.kafka.support.ProducerListener;
 import org.springframework.kafka.support.converter.RecordMessageConverter;
+import org.springframework.lang.Nullable;
 
 /**
  * An {@link IntegrationComponentSpec} implementation for the {@link KafkaTemplate}.
@@ -49,7 +50,7 @@ public class KafkaTemplateSpec<K, V>
 	}
 
 	@Override
-	public KafkaTemplateSpec<K, V> id(String id) { // NOSONAR - visibility
+	public KafkaTemplateSpec<K, V> id(@Nullable String id) { // NOSONAR - visibility
 		return super.id(id);
 	}
 

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

@@ -1,4 +1,6 @@
 /**
  * Provides Spring Integration Java DSL Components support for Apache Kafka.
  */
+@org.springframework.lang.NonNullApi
+@org.springframework.lang.NonNullFields
 package org.springframework.integration.kafka.dsl;