GH-3912: Handler: ignore Groovy generated methods

Fixes https://github.com/spring-projects/spring-integration/issues/3912

**Cherry-pick to `5.5.x`**

spring-integration-core/src/main/java/org/springframework/integration/handler/support/MessagingMethodInvokerHelper.java

@@ -53,6 +53,7 @@ import org.springframework.core.KotlinDetector;
 import org.springframework.core.LocalVariableTableParameterNameDiscoverer;
 import org.springframework.core.MethodParameter;
 import org.springframework.core.ParameterNameDiscoverer;
+import org.springframework.core.annotation.AnnotatedElementUtils;
 import org.springframework.core.annotation.AnnotationAttributes;
 import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.core.convert.ConversionFailedException;
@@ -759,7 +760,7 @@ public class MessagingMethodInvokerHelper extends AbstractExpressionEvaluator im
 						ambiguousFallbackType, ambiguousFallbackMessageGenericType, matchesAnnotation, handlerMethod1);
 			}
 
-		}, new UniqueMethodFilter(targetClass));
+		}, ((ReflectionUtils.MethodFilter) this::isHandlerMethod).and(new UniqueMethodFilter(targetClass)));
 
 		if (candidateMethods.isEmpty() && candidateMessageMethods.isEmpty() && fallbackMethods.isEmpty()
 				&& fallbackMessageMethods.isEmpty()) {
@@ -767,36 +768,16 @@ public class MessagingMethodInvokerHelper extends AbstractExpressionEvaluator im
 		}
 	}
 
-	@Nullable
-	private HandlerMethod obtainHandlerMethodIfAny(Method methodToProcess) {
-		HandlerMethod handlerMethodToUse = null;
-		if (isMethodEligible(methodToProcess)) {
-			try {
-				handlerMethodToUse = createHandlerMethod(
-						AopUtils.selectInvocableMethod(methodToProcess, ClassUtils.getUserClass(this.targetObject)));
-			}
-			catch (Exception ex) {
-				LOGGER.debug(ex, "Method [" + methodToProcess + "] is not eligible for Message handling.");
-				return null;
-			}
-
-			if (AnnotationUtils.getAnnotation(methodToProcess, Default.class) != null) {
-				Assert.state(this.defaultHandlerMethod == null,
-						() -> "Only one method can be @Default, but there are more for: " + this.targetObject);
-				this.defaultHandlerMethod = handlerMethodToUse;
-			}
-		}
-
-		return handlerMethodToUse;
-	}
-
-	private boolean isMethodEligible(Method methodToProcess) {
-		return !(methodToProcess.isBridge() || // NOSONAR boolean complexity
-				isMethodDefinedOnObjectClass(methodToProcess) ||
-				methodToProcess.getDeclaringClass().equals(Proxy.class) ||
-				(this.requiresReply && void.class.equals(methodToProcess.getReturnType())) ||
-				(this.methodName != null && !this.methodName.equals(methodToProcess.getName())) ||
-				(this.methodName == null && isPausableMethod(methodToProcess)));
+	private boolean isHandlerMethod(Method method) {
+		Class<?> declaringClass = method.getDeclaringClass();
+		return !(method.isSynthetic() ||
+				ReflectionUtils.isObjectMethod(method) ||
+				AnnotatedElementUtils.isAnnotated(method, "groovy.transform.Generated") ||
+				declaringClass.getName().equals("groovy.lang.GroovyObject") ||
+				declaringClass.equals(Proxy.class) ||
+				(this.requiresReply && void.class.equals(method.getReturnType())) ||
+				(this.methodName != null && !this.methodName.equals(method.getName())) ||
+				(this.methodName == null && isPausableMethod(method)));
 	}
 
 	private boolean isPausableMethod(Method pausableMethod) {
@@ -811,6 +792,27 @@ public class MessagingMethodInvokerHelper extends AbstractExpressionEvaluator im
 		return pausable;
 	}
 
+	@Nullable
+	private HandlerMethod obtainHandlerMethodIfAny(Method methodToProcess) {
+		HandlerMethod handlerMethodToUse;
+		try {
+			handlerMethodToUse = createHandlerMethod(
+					AopUtils.selectInvocableMethod(methodToProcess, ClassUtils.getUserClass(this.targetObject)));
+		}
+		catch (Exception ex) {
+			LOGGER.debug(ex, "Method [" + methodToProcess + "] is not eligible for Message handling.");
+			return null;
+		}
+
+		if (AnnotationUtils.getAnnotation(methodToProcess, Default.class) != null) {
+			Assert.state(this.defaultHandlerMethod == null,
+					() -> "Only one method can be @Default, but there are more for: " + this.targetObject);
+			this.defaultHandlerMethod = handlerMethodToUse;
+		}
+
+		return handlerMethodToUse;
+	}
+
 	private void populateHandlerMethod(Map<Class<?>, HandlerMethod> candidateMethods,
 			Map<Class<?>, HandlerMethod> candidateMessageMethods, Map<Class<?>, HandlerMethod> fallbackMethods,
 			Map<Class<?>, HandlerMethod> fallbackMessageMethods, AtomicReference<Class<?>> ambiguousFallbackType,
@@ -1013,8 +1015,7 @@ public class MessagingMethodInvokerHelper extends AbstractExpressionEvaluator im
 
 	private static boolean isMethodDefinedOnObjectClass(Method method) {
 		return method != null && // NOSONAR
-				(method.getDeclaringClass().equals(Object.class) || ReflectionUtils.isEqualsMethod(method) ||
-						ReflectionUtils.isHashCodeMethod(method) || ReflectionUtils.isToStringMethod(method) ||
+				(ReflectionUtils.isObjectMethod(method) ||
 						AopUtils.isFinalizeMethod(method) || (method.getName().equals("clone")
 						&& method.getParameterTypes().length == 0));
 	}

spring-integration-groovy/src/test/groovy/org/springframework/integration/groovy/dsl/test/GroovyDslTests.groovy

@@ -16,7 +16,7 @@
 
 package org.springframework.integration.groovy.dsl.test
 
-
+import groovy.transform.CompileStatic
 import org.junit.jupiter.api.Test
 import org.springframework.beans.factory.BeanFactory
 import org.springframework.beans.factory.annotation.Autowired
@@ -45,6 +45,7 @@ import reactor.core.publisher.Flux
 import reactor.test.StepVerifier
 
 import java.time.Duration
+import java.util.concurrent.atomic.AtomicReference
 import java.util.function.Function
 
 import static org.springframework.integration.groovy.dsl.IntegrationGroovyDsl.integrationFlow
@@ -196,6 +197,19 @@ class GroovyDslTests {
 		assert this.wireTapChannel.receive(10_000)?.payload == 'test'
 	}
 
+	@Autowired
+	@Qualifier('externalServiceFlow.input')
+	private MessageChannel externalServiceFlowInput
+
+	@Autowired
+	GroovyTestService groovyTestService
+
+	@Test
+	void 'handle service'() {
+		this.externalServiceFlowInput.send(new GenericMessage<Object>('test'))
+		assert groovyTestService.result.get() == 'TEST'
+	}
+
 	@Configuration
 	@EnableIntegration
 	static class Config {
@@ -301,6 +315,30 @@ class GroovyDslTests {
 			}
 		}
 
+		@Bean
+		myService() {
+			new GroovyTestService()
+		}
+
+		@Bean
+		externalServiceFlow(GroovyTestService groovyTestService) {
+			integrationFlow {
+				handle groovyTestService
+			}
+
+		}
+
+	}
+
+	@CompileStatic
+	static class GroovyTestService {
+
+		AtomicReference<String> result = new AtomicReference<>()
+
+		void handlePayload(String payload) {
+			result.set payload.toUpperCase()
+		}
+
 	}
 
 }