GH-186 - Workaround for invalid application listener matching in AbstractApplicationEventMulticaster.

AbstractApplicationEventMulticaster.supportsEvent(…) currently doesn't properly match unresolved, generic ApplicationEvents (see [0]). We now work around this problem by additionally matching the raw event types in a custom override of supportsEvent(…).

[0] spring-projects/spring-framework#30399

Author: odrotbohm

spring-modulith-events/spring-modulith-events-core/src/main/java/org/springframework/modulith/events/support/PersistentApplicationEventMulticaster.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.modulith.events.support;
 
+import java.lang.reflect.Field;
 import java.util.Collection;
 import java.util.List;
 import java.util.function.Consumer;
@@ -29,6 +30,7 @@
 import org.springframework.context.PayloadApplicationEvent;
 import org.springframework.context.event.AbstractApplicationEventMulticaster;
 import org.springframework.context.event.ApplicationEventMulticaster;
+import org.springframework.context.event.ApplicationListenerMethodAdapter;
 import org.springframework.core.ResolvableType;
 import org.springframework.core.annotation.AnnotationAwareOrderComparator;
 import org.springframework.lang.NonNull;
@@ -39,6 +41,7 @@
 import org.springframework.transaction.event.TransactionalApplicationListener;
 import org.springframework.transaction.event.TransactionalEventListener;
 import org.springframework.util.Assert;
+import org.springframework.util.ReflectionUtils;
 
 /**
  * An {@link ApplicationEventMulticaster} to register {@link EventPublication}s in an {@link EventPublicationRegistry}
@@ -55,9 +58,15 @@ public class PersistentApplicationEventMulticaster extends AbstractApplicationEv
 		implements SmartInitializingSingleton {
 
 	private static final Logger LOGGER = LoggerFactory.getLogger(PersistentApplicationEventMulticaster.class);
+	private static final Field DECLARED_EVENT_TYPES_FIELD = ReflectionUtils
+			.findField(ApplicationListenerMethodAdapter.class, "declaredEventTypes");
 
 	private final @NonNull Supplier<EventPublicationRegistry> registry;
 
+	static {
+		ReflectionUtils.makeAccessible(DECLARED_EVENT_TYPES_FIELD);
+	}
+
 	/**
 	 * Creates a new {@link PersistentApplicationEventMulticaster} for the given {@link EventPublicationRegistry}.
 	 *
@@ -118,6 +127,34 @@ public void afterSingletonsInstantiated() {
 		publications.forEach(this::invokeTargetListener);
 	}
 
+	/**
+	 * Temporary workaround for an issue in Spring Framework that lets ApplicationListenerMethodAdapter match all generic
+	 * events with unresolved generics.
+	 *
+	 * @see <a href=
+	 *      "https://github.com/spring-projects/spring-framework/issues/30399">https://github.com/spring-projects/spring-framework/issues/30399</a>
+	 */
+	@Override
+	@SuppressWarnings("unchecked")
+	protected boolean supportsEvent(ApplicationListener<?> listener, ResolvableType eventType, Class<?> sourceType) {
+
+		var result = super.supportsEvent(listener, eventType, sourceType);
+
+		if (!super.supportsEvent(listener, eventType, sourceType)
+				|| !(listener instanceof ApplicationListenerMethodAdapter adapter)) {
+			return result;
+		}
+
+		var actualEventType = ResolvableType.forClass(PayloadApplicationEvent.class).isAssignableFrom(eventType)
+				? eventType.getGeneric()
+				: eventType;
+
+		var declaredEventTypes = (List<ResolvableType>) ReflectionUtils.getField(DECLARED_EVENT_TYPES_FIELD, adapter);
+
+		return declaredEventTypes.stream()
+				.anyMatch(it -> it.isAssignableFrom(actualEventType.getRawClass()));
+	}
+
 	private void invokeTargetListener(EventPublication publication) {
 
 		var listeners = new TransactionalEventListeners(

spring-modulith-events/spring-modulith-events-core/src/test/java/org/springframework/modulith/events/support/PersistentApplicationEventMulticasterIntegrationTests.java

@@ -0,0 +1,90 @@
+/*
+ * Copyright 2023 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.modulith.events.support;
+
+import static org.mockito.ArgumentMatchers.*;
+import static org.mockito.Mockito.*;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.ApplicationEvent;
+import org.springframework.context.ApplicationEventPublisher;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.modulith.events.EventPublication;
+import org.springframework.modulith.events.EventPublicationRepository;
+import org.springframework.modulith.events.config.EnablePersistentDomainEvents;
+import org.springframework.stereotype.Component;
+import org.springframework.test.context.junit.jupiter.SpringExtension;
+import org.springframework.transaction.annotation.EnableTransactionManagement;
+import org.springframework.transaction.event.TransactionalEventListener;
+
+/**
+ * Integration test for {@link PersistentApplicationEventMulticaster}.
+ *
+ * @author Oliver Drotbohm
+ */
+@ExtendWith(SpringExtension.class)
+class PersistentApplicationEventMulticasterIntegrationTests {
+
+	@Configuration
+	@EnableTransactionManagement
+	@EnablePersistentDomainEvents
+	static class TestConfiguration {
+
+		@Bean
+		EventPublicationRepository repository() {
+			return mock(EventPublicationRepository.class);
+		}
+
+		@Bean
+		SampleEventListener listener() {
+			return new SampleEventListener();
+		}
+	}
+
+	@Autowired ApplicationEventPublisher publisher;
+	@Autowired EventPublicationRepository repository;
+
+	@Test // GH-186
+	void doesNotPublishGenericEventsToListeners() throws Exception {
+
+		publisher.publishEvent(new SomeGenericEvent<>());
+		verify(repository, never()).create(any(EventPublication.class));
+
+		publisher.publishEvent(new SomeOtherEvent());
+		verify(repository).create(any(EventPublication.class));
+	}
+
+	@Component
+	static class SampleEventListener {
+
+		@TransactionalEventListener
+		void listener(SomeOtherEvent event) {}
+	}
+
+	static class SomeGenericEvent<T> extends ApplicationEvent {
+
+		private static final long serialVersionUID = -4054955298417761460L;
+
+		public SomeGenericEvent() {
+			super(new Object());
+		}
+	}
+
+	static class SomeOtherEvent {}
+}