GH-9492: Honor @Nested in @SpringIntegrationTest

Fixes: #9492
Issue link: https://github.com/spring-projects/spring-integration/issues/9492

Switches `MockIntegrationContextCustomizerFactory` & `SpringIntegrationTestExecutionListener`
to use `TestContextAnnotationUtils` in order to properly support
`@NestedTestConfiguration` semantics.

Adds an integration test with a base class and several
`@Nested` inner test classes to verify the various
permutations of `@SpringIntegrationTest` inherit/override
behavior when used w/ `@NestedTestConfiguration`.

**Auto-cherry-pick to `6.3.x` & `6.2.x`**

spring-integration-test/src/test/java/org/springframework/integration/test/context/AbstractIntegrationTest.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2024 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.integration.test.context;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.integration.config.EnableIntegration;
+import org.springframework.integration.endpoint.AbstractEndpoint;
+import org.springframework.integration.endpoint.ReactiveMessageSourceProducer;
+import org.springframework.messaging.support.GenericMessage;
+import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
+
+/**
+ * Base integration test that specifies a default {@link SpringIntegrationTest}
+ * to be inherited by concrete subclasses.
+ *
+ * @author Chris Bono
+ *
+ * @since 6.2.10
+ */
+@SpringJUnitConfig
+@SpringIntegrationTest(noAutoStartup = "*")
+class AbstractIntegrationTest {
+
+	@Configuration(proxyBeanMethods = false)
+	@EnableIntegration
+	static class MockEndpointConfig {
+
+		@Bean
+		AbstractEndpoint mockEndpoint() {
+			ReactiveMessageSourceProducer endpoint =
+					new ReactiveMessageSourceProducer(() -> new GenericMessage<>("testFromMockEndpoint"));
+			endpoint.setOutputChannelName("nullChannel");
+			return endpoint;
+		}
+
+	}
+}

spring-integration-test/src/test/java/org/springframework/integration/test/context/NestedSpringIntegrationTestAnnotationTests.java

@@ -0,0 +1,95 @@
+/*
+ * Copyright 2024 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.integration.test.context;
+
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.integration.endpoint.AbstractEndpoint;
+import org.springframework.lang.Nullable;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.NestedTestConfiguration;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Concrete specialization of {@link AbstractIntegrationTest} used to
+ * test inherit and override behavior of {@link SpringIntegrationTest}
+ * when used with {@link Nested} and {@link NestedTestConfiguration}.
+ *
+ * @author Chris Bono
+ * @author Artem Bilan
+ *
+ * @since 6.2.10
+ */
+class NestedSpringIntegrationTestAnnotationTests extends AbstractIntegrationTest {
+
+	@Test
+	void annotationDefinedOnParentIsInheritedByDefault(@Autowired AbstractEndpoint mockEndpoint) {
+		assertThat(mockEndpoint.isRunning()).isFalse();
+	}
+
+	@Nested
+	class NestedTestDefaultEnclosingConfiguration {
+
+		@Test
+		void annotationDefinedOnParentOfEnclosingIsInheritedByDefault(@Autowired AbstractEndpoint mockEndpoint) {
+			assertThat(mockEndpoint.isRunning()).isFalse();
+		}
+
+	}
+
+	@Nested
+	@NestedTestConfiguration(NestedTestConfiguration.EnclosingConfiguration.INHERIT)
+	class NestedTestWithInheritEnclosingConfiguration {
+
+		@Test
+		void annotationDefinedOnParentOfEnclosingIsInherited(@Autowired AbstractEndpoint mockEndpoint) {
+			assertThat(mockEndpoint.isRunning()).isFalse();
+		}
+
+	}
+
+	@Nested
+	@NestedTestConfiguration(NestedTestConfiguration.EnclosingConfiguration.INHERIT)
+	@SpringIntegrationTest(noAutoStartup = "noSuchEndpointWithThisPatternExists")
+	class NestedTestWithInheritEnclosingConfigurationButOverrideAnnotation {
+
+		@Test
+		void annotationDefinedOnParentOfEnclosingIsOverridden(@Autowired AbstractEndpoint mockEndpoint) {
+			assertThat(mockEndpoint.isRunning()).isTrue();
+		}
+
+	}
+
+	@Nested
+	@NestedTestConfiguration(NestedTestConfiguration.EnclosingConfiguration.OVERRIDE)
+	@ContextConfiguration(classes = MockEndpointConfig.class)
+	class NestedTestWithOverrideEnclosingConfiguration {
+
+		@Test
+		void annotationDefinedOnParentOfEnclosingIsIgnored(@Autowired AbstractEndpoint mockEndpoint,
+				@Nullable @Autowired MockIntegrationContext mockIntegrationContext) {
+
+			assertThat(mockEndpoint.isRunning()).isTrue();
+			assertThat(mockIntegrationContext).isNull();
+		}
+
+	}
+
+}