Adding jspecify nullability checks in transaction package

spring-kafka/src/main/java/org/springframework/kafka/transaction/KafkaTransactionManager.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2020 the original author or authors.
+ * Copyright 2017-2025 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 +18,8 @@
 
 import java.time.Duration;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.kafka.core.KafkaResourceHolder;
 import org.springframework.kafka.core.ProducerFactory;
 import org.springframework.kafka.core.ProducerFactoryUtils;
@@ -45,8 +47,8 @@
  * <p>
  * Application code is required to retrieve the transactional Kafka resources via
  * {@link ProducerFactoryUtils#getTransactionalResourceHolder(ProducerFactory, String, java.time.Duration)}.
- * Spring's {@link org.springframework.kafka.core.KafkaTemplate KafkaTemplate} will auto
- * detect a thread-bound Producer and automatically participate in it.
+ * Spring's {@link org.springframework.kafka.core.KafkaTemplate KafkaTemplate} will auto-detect
+ * a thread-bound Producer and automatically participate in it.
  *
  * <p>
  * <b>The use of {@link org.springframework.kafka.core.DefaultKafkaProducerFactory
@@ -63,6 +65,7 @@
  * @param <V> the value type.
  *
  * @author Gary Russell
+ * @author Soby Chacko
  */
 @SuppressWarnings("serial")
 public class KafkaTransactionManager<K, V> extends AbstractPlatformTransactionManager
@@ -72,7 +75,7 @@ public class KafkaTransactionManager<K, V> extends AbstractPlatformTransactionMa
 
 	private final ProducerFactory<K, V> producerFactory;
 
-	private String transactionIdPrefix;
+	private @Nullable String transactionIdPrefix;
 
 	private Duration closeTimeout = ProducerFactoryUtils.DEFAULT_CLOSE_TIMEOUT;
 
@@ -121,7 +124,7 @@ public void setCloseTimeout(Duration closeTimeout) {
 	@SuppressWarnings(UNCHECKED)
 	@Override
 	protected Object doGetTransaction() {
-		KafkaTransactionObject<K, V> txObject = new KafkaTransactionObject<K, V>();
+		KafkaTransactionObject<K, V> txObject = new KafkaTransactionObject<>();
 		txObject.setResourceHolder((KafkaResourceHolder<K, V>) TransactionSynchronizationManager
 				.getResource(getProducerFactory()));
 		return txObject;
@@ -149,10 +152,10 @@ protected void doBegin(Object transaction, TransactionDefinition definition) {
 				logger.debug("Created Kafka transaction on producer [" + resourceHolder.getProducer() + "]");
 			}
 			txObject.setResourceHolder(resourceHolder);
-			txObject.getResourceHolder().setSynchronizedWithTransaction(true);
+			resourceHolder.setSynchronizedWithTransaction(true);
 			int timeout = determineTimeout(definition);
 			if (timeout != TransactionDefinition.TIMEOUT_DEFAULT) {
-				txObject.getResourceHolder().setTimeoutInSeconds(timeout);
+				resourceHolder.setTimeoutInSeconds(timeout);
 			}
 		}
 		catch (Exception ex) {
@@ -172,9 +175,13 @@ protected Object doSuspend(Object transaction) {
 	}
 
 	@Override
-	protected void doResume(Object transaction, Object suspendedResources) {
-		@SuppressWarnings(UNCHECKED)
+	@SuppressWarnings(UNCHECKED)
+	protected void doResume(@Nullable Object transaction, Object suspendedResources) {
 		KafkaResourceHolder<K, V> producerHolder = (KafkaResourceHolder<K, V>) suspendedResources;
+		if (transaction != null) {
+			KafkaTransactionObject<K, V> txObject = (KafkaTransactionObject<K, V>) transaction;
+			txObject.setResourceHolder(producerHolder);
+		}
 		TransactionSynchronizationManager.bindResource(getProducerFactory(), producerHolder);
 	}
 
@@ -183,31 +190,41 @@ protected void doCommit(DefaultTransactionStatus status) {
 		@SuppressWarnings(UNCHECKED)
 		KafkaTransactionObject<K, V> txObject = (KafkaTransactionObject<K, V>) status.getTransaction();
 		KafkaResourceHolder<K, V> resourceHolder = txObject.getResourceHolder();
-		resourceHolder.commit();
+		if (resourceHolder != null) {
+			resourceHolder.commit();
+		}
 	}
 
 	@Override
 	protected void doRollback(DefaultTransactionStatus status) {
 		@SuppressWarnings(UNCHECKED)
 		KafkaTransactionObject<K, V> txObject = (KafkaTransactionObject<K, V>) status.getTransaction();
 		KafkaResourceHolder<K, V> resourceHolder = txObject.getResourceHolder();
-		resourceHolder.rollback();
+		if (resourceHolder != null) {
+			resourceHolder.rollback();
+		}
 	}
 
 	@Override
 	protected void doSetRollbackOnly(DefaultTransactionStatus status) {
 		@SuppressWarnings(UNCHECKED)
 		KafkaTransactionObject<K, V> txObject = (KafkaTransactionObject<K, V>) status.getTransaction();
-		txObject.getResourceHolder().setRollbackOnly();
+		KafkaResourceHolder<K, V> kafkaResourceHolder = txObject.getResourceHolder();
+		if (kafkaResourceHolder != null) {
+			kafkaResourceHolder.setRollbackOnly();
+		}
 	}
 
 	@Override
 	protected void doCleanupAfterCompletion(Object transaction) {
 		@SuppressWarnings(UNCHECKED)
 		KafkaTransactionObject<K, V> txObject = (KafkaTransactionObject<K, V>) transaction;
 		TransactionSynchronizationManager.unbindResource(getProducerFactory());
-		txObject.getResourceHolder().close();
-		txObject.getResourceHolder().clear();
+		KafkaResourceHolder<K, V> kafkaResourceHolder = txObject.getResourceHolder();
+		if (kafkaResourceHolder != null) {
+			kafkaResourceHolder.close();
+			kafkaResourceHolder.clear();
+		}
 	}
 
 	/**
@@ -217,22 +234,22 @@ protected void doCleanupAfterCompletion(Object transaction) {
 	 */
 	private static class KafkaTransactionObject<K, V> implements SmartTransactionObject {
 
-		private KafkaResourceHolder<K, V> resourceHolder;
+		private @Nullable KafkaResourceHolder<K, V> resourceHolder;
 
 		KafkaTransactionObject() {
 		}
 
-		public void setResourceHolder(KafkaResourceHolder<K, V> resourceHolder) {
+		public void setResourceHolder(@Nullable KafkaResourceHolder<K, V> resourceHolder) {
 			this.resourceHolder = resourceHolder;
 		}
 
-		public KafkaResourceHolder<K, V> getResourceHolder() {
+		public @Nullable KafkaResourceHolder<K, V> getResourceHolder() {
 			return this.resourceHolder;
 		}
 
 		@Override
 		public boolean isRollbackOnly() {
-			return this.resourceHolder.isRollbackOnly();
+			return this.resourceHolder != null && this.resourceHolder.isRollbackOnly();
 		}
 
 		@Override

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

@@ -1,4 +1,5 @@
 /**
  * Provides classes related to transactions.
  */
+@org.jspecify.annotations.NullMarked
 package org.springframework.kafka.transaction;

spring-kafka/src/test/java/org/springframework/kafka/core/KafkaTemplateTransactionTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2024 the original author or authors.
+ * Copyright 2017-2025 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.
@@ -42,6 +42,7 @@
 import org.apache.kafka.common.serialization.StringDeserializer;
 import org.apache.kafka.common.serialization.StringSerializer;
 import org.assertj.core.api.Assertions;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 import org.mockito.InOrder;
 
@@ -57,7 +58,6 @@
 import org.springframework.kafka.test.context.EmbeddedKafka;
 import org.springframework.kafka.test.utils.KafkaTestUtils;
 import org.springframework.kafka.transaction.KafkaTransactionManager;
-import org.springframework.lang.Nullable;
 import org.springframework.transaction.TransactionDefinition;
 import org.springframework.transaction.TransactionException;
 import org.springframework.transaction.annotation.EnableTransactionManagement;