Nullability improvements in KafkaProducerFactory classes

Signed-off-by: Soby Chacko <soby.chacko@broadcom.com>

spring-kafka/src/main/java/org/springframework/kafka/core/DefaultKafkaProducerFactory.java

@@ -144,13 +144,13 @@ public class DefaultKafkaProducerFactory<K, V> extends KafkaResourceFactory
 
 	private TransactionIdSuffixStrategy transactionIdSuffixStrategy = new DefaultTransactionIdSuffixStrategy(0);
 
-	private @Nullable Supplier<Serializer<K>> keySerializerSupplier;
+	private @Nullable Supplier<@Nullable Serializer<K>> keySerializerSupplier;
 
-	private @Nullable Supplier<Serializer<V>> valueSerializerSupplier;
+	private @Nullable Supplier<@Nullable Serializer<V>> valueSerializerSupplier;
 
-	private @Nullable Supplier<Serializer<K>> rawKeySerializerSupplier;
+	private @Nullable Supplier<@Nullable Serializer<K>> rawKeySerializerSupplier;
 
-	private @Nullable Supplier<Serializer<V>> rawValueSerializerSupplier;
+	private @Nullable Supplier<@Nullable Serializer<V>> rawValueSerializerSupplier;
 
 	private Duration physicalCloseTimeout = DEFAULT_PHYSICAL_CLOSE_TIMEOUT;
 
@@ -230,8 +230,8 @@ public class DefaultKafkaProducerFactory<K, V> extends KafkaResourceFactory
 	 * @since 2.3
 	 */
 	public DefaultKafkaProducerFactory(Map<String, Object> configs,
-			@Nullable Supplier<Serializer<K>> keySerializerSupplier,
-			@Nullable Supplier<Serializer<V>> valueSerializerSupplier) {
+			@Nullable Supplier<@Nullable Serializer<K>> keySerializerSupplier,
+			@Nullable Supplier<@Nullable Serializer<V>> valueSerializerSupplier) {
 
 		this(configs, keySerializerSupplier, valueSerializerSupplier, true);
 	}
@@ -252,8 +252,8 @@ public class DefaultKafkaProducerFactory<K, V> extends KafkaResourceFactory
 	 * @since 2.8.7
 	 */
 	public DefaultKafkaProducerFactory(Map<String, Object> configs,
-			@Nullable Supplier<Serializer<K>> keySerializerSupplier,
-			@Nullable Supplier<Serializer<V>> valueSerializerSupplier, boolean configureSerializers) {
+			@Nullable Supplier<@Nullable Serializer<K>> keySerializerSupplier,
+			@Nullable Supplier<@Nullable Serializer<V>> valueSerializerSupplier, boolean configureSerializers) {
 
 		this.configs = new ConcurrentHashMap<>(configs);
 		this.configureSerializers = configureSerializers;
@@ -269,7 +269,8 @@ public class DefaultKafkaProducerFactory<K, V> extends KafkaResourceFactory
 		}
 	}
 
-	private @Nullable Supplier<Serializer<K>> keySerializerSupplier(@Nullable Supplier<Serializer<K>> keySerializerSupplier) {
+	private @Nullable Supplier<@Nullable Serializer<K>> keySerializerSupplier(
+			@Nullable Supplier<@Nullable Serializer<K>> keySerializerSupplier) {
 		this.rawKeySerializerSupplier = keySerializerSupplier;
 		if (!this.configureSerializers) {
 			return keySerializerSupplier;
@@ -285,7 +286,8 @@ public class DefaultKafkaProducerFactory<K, V> extends KafkaResourceFactory
 		};
 	}
 
-	private @Nullable Supplier<Serializer<V>> valueSerializerSupplier(@Nullable Supplier<Serializer<V>> valueSerializerSupplier) {
+	private @Nullable Supplier<@Nullable Serializer<V>> valueSerializerSupplier(
+			@Nullable Supplier<@Nullable Serializer<V>> valueSerializerSupplier) {
 		this.rawValueSerializerSupplier = valueSerializerSupplier;
 		if (!this.configureSerializers) {
 			return valueSerializerSupplier;
@@ -341,7 +343,7 @@ public class DefaultKafkaProducerFactory<K, V> extends KafkaResourceFactory
 	 * @since 2.8
 	 * @see #setConfigureSerializers(boolean)
 	 */
-	public void setKeySerializerSupplier(Supplier<Serializer<K>> keySerializerSupplier) {
+	public void setKeySerializerSupplier(@Nullable Supplier<@Nullable Serializer<K>> keySerializerSupplier) {
 		this.keySerializerSupplier = keySerializerSupplier(keySerializerSupplier);
 	}
 
@@ -353,7 +355,7 @@ public class DefaultKafkaProducerFactory<K, V> extends KafkaResourceFactory
 	 * @since 2.8
 	 * @see #setConfigureSerializers(boolean)
 	 */
-	public void setValueSerializerSupplier(Supplier<Serializer<V>> valueSerializerSupplier) {
+	public void setValueSerializerSupplier(@Nullable Supplier<@Nullable Serializer<V>> valueSerializerSupplier) {
 		this.valueSerializerSupplier = valueSerializerSupplier(valueSerializerSupplier);
 	}
 
@@ -469,13 +471,13 @@ public class DefaultKafkaProducerFactory<K, V> extends KafkaResourceFactory
 
 	@Override
 	@Nullable
-	public Supplier<Serializer<K>> getKeySerializerSupplier() {
+	public Supplier<@Nullable Serializer<K>> getKeySerializerSupplier() {
 		return this.rawKeySerializerSupplier;
 	}
 
 	@Override
 	@Nullable
-	public Supplier<Serializer<V>> getValueSerializerSupplier() {
+	public Supplier<@Nullable Serializer<V>> getValueSerializerSupplier() {
 		return this.rawValueSerializerSupplier;
 	}
 
@@ -696,7 +698,6 @@ public class DefaultKafkaProducerFactory<K, V> extends KafkaResourceFactory
 		return this.transactionIdPrefix != null;
 	}
 
-	@SuppressWarnings("resource")
 	@Override
 	public void destroy() {
 		CloseSafeProducer<K, V> producerToClose;

spring-kafka/src/main/java/org/springframework/kafka/core/ProducerFactory.java

@@ -115,7 +115,7 @@ public interface ProducerFactory<K, V> {
 	 * @since 2.5
 	 */
 	@Nullable
-	default Supplier<Serializer<V>> getValueSerializerSupplier() {
+	default Supplier<@Nullable Serializer<V>> getValueSerializerSupplier() {
 		return () -> null;
 	}
 
@@ -126,7 +126,7 @@ public interface ProducerFactory<K, V> {
 	 * @since 2.5
 	 */
 	@Nullable
-	default Supplier<Serializer<K>> getKeySerializerSupplier() {
+	default Supplier<@Nullable Serializer<K>> getKeySerializerSupplier() {
 		return () -> null;
 	}