Fix SpringIntegrationTestExecutionListener for restart

Related to: spring-projects/spring-framework#35168

Spring Framework has introduced recently an optimization for cached contexts.
So, if one is not used, it is stopped in the cache.
When we pull it next time from there, it is restarted.
The `SpringIntegrationTestExecutionListener` ha a flaw to change the state of the endpoints
in the application context, but never reset it back to original.
The problem has become apparent because of not reset auto-startup status of endpoints and that `AC.restart()`

* Fix `SpringIntegrationTestExecutionListener` to use `setAutoStartup(false)`
on `autoStartupCandidates` in the `afterTestClass()`.
This is exactly a state the `MockIntegrationContext` has gathered them in its initialization phase.
* Fix `MockIntegrationContext.autoStartupCandidates` to be a `Set` instead.
The point is that `postProcessBeforeInitialization()` deals with `AbstractEndpoint` beans.
And then `afterSingletonsInstantiated()` also gathers those beans from the `BeanFactory`.
So, with a `Set` we aim for no duplications

Author: artembilan

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

@@ -16,11 +16,11 @@
 
 package org.springframework.integration.test.context;
 
-import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
-import java.util.List;
+import java.util.HashSet;
+import java.util.Set;
 
 import reactor.core.publisher.Mono;
 
@@ -79,7 +79,7 @@ public class MockIntegrationContext implements BeanPostProcessor, SmartInitializ
 
 	private final MultiValueMap<String, Object> beans = new LinkedMultiValueMap<>();
 
-	private final List<AbstractEndpoint> autoStartupCandidates = new ArrayList<>();
+	private final Set<AbstractEndpoint> autoStartupCandidates = new HashSet<>();
 
 	private ConfigurableListableBeanFactory beanFactory;
 
@@ -99,8 +99,9 @@ public Object postProcessBeforeInitialization(Object bean, String beanName) thro
 	}
 
 	private void addAutoStartupCandidates(AbstractEndpoint endpoint) {
-		endpoint.setAutoStartup(false);
-		this.autoStartupCandidates.add(endpoint);
+		if (this.autoStartupCandidates.add(endpoint)) {
+			endpoint.setAutoStartup(false);
+		}
 	}
 
 	@Override
@@ -112,8 +113,8 @@ public void afterSingletonsInstantiated() {
 				.forEach(this::addAutoStartupCandidates);
 	}
 
-	List<AbstractEndpoint> getAutoStartupCandidates() {
-		return Collections.unmodifiableList(this.autoStartupCandidates);
+	Set<AbstractEndpoint> getAutoStartupCandidates() {
+		return Collections.unmodifiableSet(this.autoStartupCandidates);
 	}
 
 	/**

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

@@ -17,7 +17,7 @@
 package org.springframework.integration.test.context;
 
 import java.util.Arrays;
-import java.util.List;
+import java.util.Set;
 
 import org.springframework.context.ApplicationContext;
 import org.springframework.integration.endpoint.AbstractEndpoint;
@@ -37,7 +37,7 @@
  */
 class SpringIntegrationTestExecutionListener implements TestExecutionListener {
 
-	private List<AbstractEndpoint> autoStartupCandidates;
+	private Set<AbstractEndpoint> autoStartupCandidates;
 
 	@Override
 	public void prepareTestInstance(TestContext testContext) {
@@ -49,16 +49,17 @@ public void prepareTestInstance(TestContext testContext) {
 		ApplicationContext applicationContext = testContext.getApplicationContext();
 		MockIntegrationContext mockIntegrationContext = applicationContext.getBean(MockIntegrationContext.class);
 		this.autoStartupCandidates = mockIntegrationContext.getAutoStartupCandidates();
-		this.autoStartupCandidates
-				.stream()
+		this.autoStartupCandidates.stream()
 				.filter(endpoint -> !match(endpoint.getBeanName(), patterns))
 				.peek(endpoint -> endpoint.setAutoStartup(true))
 				.forEach(AbstractEndpoint::start);
 	}
 
 	@Override
 	public void afterTestClass(TestContext testContext) {
-		this.autoStartupCandidates.forEach(AbstractEndpoint::stop);
+		this.autoStartupCandidates.stream()
+				.peek(endpoint -> endpoint.setAutoStartup(false))
+				.forEach(AbstractEndpoint::stop);
 	}
 
 	private static boolean match(String name, String[] patterns) {