GH-10083: Apply Nullability into test module

spring-integration-test/src/main/java/org/springframework/integration/test/context/MockIntegrationContext.java

@@ -81,6 +81,7 @@ public class MockIntegrationContext implements BeanPostProcessor, SmartInitializ
 
 	private final Set<AbstractEndpoint> autoStartupCandidates = new HashSet<>();
 
+	@SuppressWarnings("NullAway.Init")
 	private ConfigurableListableBeanFactory beanFactory;
 
 	@Override
@@ -229,11 +230,14 @@ public void substituteMessageHandlerFor(String consumerEndpointId, // NOSONAR -
 		if (mockMessageHandler instanceof MessageProducer mockMessageProducer) {
 			if (targetMessageHandler instanceof MessageProducer messageProducer) {
 				MessageChannel outputChannel = messageProducer.getOutputChannel();
-				mockMessageProducer.setOutputChannel(outputChannel);
+				if (outputChannel != null) {
+					mockMessageProducer.setOutputChannel(outputChannel);
+				}
 			}
 			else {
 				if (mockMessageHandler instanceof MockMessageHandler) {
-					if (TestUtils.getPropertyValue(mockMessageHandler, "hasReplies", Boolean.class)) {
+					if (Boolean.TRUE.equals(TestUtils.getPropertyValue(
+							mockMessageHandler, "hasReplies", Boolean.class))) {
 						throw new IllegalStateException("The [" + mockMessageHandler + "] " +
 								"with replies can't replace simple MessageHandler [" + targetMessageHandler + "]");
 					}

spring-integration-test/src/main/java/org/springframework/integration/test/context/MockIntegrationContextCustomizerFactory.java

@@ -18,6 +18,8 @@
 
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.test.context.ContextConfigurationAttributes;
 import org.springframework.test.context.ContextCustomizer;
 import org.springframework.test.context.ContextCustomizerFactory;
@@ -38,7 +40,7 @@
 class MockIntegrationContextCustomizerFactory implements ContextCustomizerFactory {
 
 	@Override
-	public ContextCustomizer createContextCustomizer(Class<?> testClass,
+	public @Nullable ContextCustomizer createContextCustomizer(Class<?> testClass,
 			List<ContextConfigurationAttributes> configAttributes) {
 
 		return TestContextAnnotationUtils.hasAnnotation(testClass, SpringIntegrationTest.class)

spring-integration-test/src/main/java/org/springframework/integration/test/context/SpringIntegrationTestExecutionListener.java

@@ -17,6 +17,7 @@
 package org.springframework.integration.test.context;
 
 import java.util.Arrays;
+import java.util.HashSet;
 import java.util.Set;
 
 import org.springframework.context.ApplicationContext;
@@ -37,7 +38,7 @@
  */
 class SpringIntegrationTestExecutionListener implements TestExecutionListener {
 
-	private Set<AbstractEndpoint> autoStartupCandidates;
+	private Set<AbstractEndpoint> autoStartupCandidates = new HashSet<>();
 
 	@Override
 	public void prepareTestInstance(TestContext testContext) {
@@ -50,7 +51,8 @@ public void prepareTestInstance(TestContext testContext) {
 		MockIntegrationContext mockIntegrationContext = applicationContext.getBean(MockIntegrationContext.class);
 		this.autoStartupCandidates = mockIntegrationContext.getAutoStartupCandidates();
 		this.autoStartupCandidates.stream()
-				.filter(endpoint -> !match(endpoint.getBeanName(), patterns))
+				.filter(endpoint -> endpoint.getBeanName() != null
+						&& !match(endpoint.getBeanName(), patterns))
 				.peek(endpoint -> endpoint.setAutoStartup(true))
 				.forEach(AbstractEndpoint::start);
 	}

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

@@ -1,4 +1,5 @@
 /**
  * Test context-related components.
  */
+@org.jspecify.annotations.NullMarked
 package org.springframework.integration.test.context;

spring-integration-test/src/main/java/org/springframework/integration/test/mock/MockIntegration.java

@@ -19,6 +19,7 @@
 import java.util.ArrayList;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
 import org.mockito.ArgumentCaptor;
 import org.mockito.BDDMockito;
 import org.mockito.Mockito;
@@ -105,7 +106,7 @@ public static MessageSource<?> mockMessageSource(Message<?> message) {
 	 * @see Mockito#mock(Class)
 	 */
 	@SuppressWarnings("rawtypes")
-	public static MessageSource<?> mockMessageSource(Message<?> message, Message<?>... messages) {
+	public static MessageSource<?> mockMessageSource(Message<?> message, Message<?> @Nullable... messages) {
 		MessageSource messageSource = Mockito.mock(MessageSource.class);
 
 		BDDMockito.given(messageSource.receive())
@@ -127,7 +128,7 @@ public static MockMessageHandler mockMessageHandler() {
 	 * @param messageArgumentCaptor the Mockito ArgumentCaptor to capture incoming messages
 	 * @return the MockMessageHandler instance ready for interaction
 	 */
-	public static MockMessageHandler mockMessageHandler(ArgumentCaptor<Message<?>> messageArgumentCaptor) {
+	public static MockMessageHandler mockMessageHandler(@Nullable ArgumentCaptor<Message<?>> messageArgumentCaptor) {
 		return Mockito.spy(new MockMessageHandler(messageArgumentCaptor));
 	}
 

spring-integration-test/src/main/java/org/springframework/integration/test/mock/MockMessageHandler.java

@@ -24,12 +24,14 @@
 import java.util.function.Consumer;
 import java.util.function.Function;
 
+import org.jspecify.annotations.Nullable;
 import org.mockito.ArgumentCaptor;
 import org.mockito.internal.matchers.CapturingMatcher;
 
 import org.springframework.integration.handler.AbstractMessageProducingHandler;
 import org.springframework.integration.test.util.TestUtils;
 import org.springframework.messaging.Message;
+import org.springframework.util.Assert;
 
 /**
  * The {@link AbstractMessageProducingHandler} extension for the mocking purpose in tests.
@@ -61,16 +63,16 @@ public class MockMessageHandler extends AbstractMessageProducingHandler {
 
 	private final Lock lock = new ReentrantLock();
 
-	protected final List<Function<Message<?>, ?>> messageFunctions = new LinkedList<>(); // NOSONAR final
+	protected final List<Function<Message<?>, ?>> messageFunctions = new LinkedList<>();
 
-	private final CapturingMatcher<Message<?>> capturingMatcher;
+	private final @Nullable CapturingMatcher<Message<?>> capturingMatcher;
 
-	protected Function<Message<?>, ?> lastFunction; // NOSONAR
+	protected @Nullable Function<Message<?>, ?> lastFunction;
 
-	protected boolean hasReplies; // NOSONAR
+	protected boolean hasReplies;
 
 	@SuppressWarnings("unchecked")
-	protected MockMessageHandler(ArgumentCaptor<Message<?>> messageArgumentCaptor) {
+	protected MockMessageHandler(@Nullable ArgumentCaptor<Message<?>> messageArgumentCaptor) {
 		if (messageArgumentCaptor != null) {
 			this.capturingMatcher = TestUtils.getPropertyValue(messageArgumentCaptor,
 					"capturingMatcher", CapturingMatcher.class);
@@ -85,6 +87,7 @@ protected MockMessageHandler(ArgumentCaptor<Message<?>> messageArgumentCaptor) {
 	 * @param nextMessageConsumer the Consumer to handle the next incoming message.
 	 * @return this
 	 */
+	@SuppressWarnings("NullAway") // See github.com/uber/NullAway/issues/1075
 	public MockMessageHandler handleNext(Consumer<Message<?>> nextMessageConsumer) {
 		this.lastFunction = m -> {
 			nextMessageConsumer.accept(m);
@@ -127,6 +130,7 @@ protected void handleMessageInternal(Message<?> message) {
 			this.lock.unlock();
 		}
 
+		Assert.notNull(function, "function must not be null");
 		Object result = function.apply(message);
 
 		if (result != null) {

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

@@ -1,4 +1,5 @@
 /**
  * Utilities for mocking integration components.
  */
+@org.jspecify.annotations.NullMarked
 package org.springframework.integration.test.mock;