* Improve reflection in the CoroutinesUtils

Author: artembilan

spring-integration-core/src/main/java/org/springframework/integration/gateway/GatewayProxyFactoryBean.java

@@ -582,7 +582,7 @@ private Object invokeGatewayMethod(MethodInvocation invocation, boolean runningO
 		Object continuation = null;
 		if (gateway.isSuspendingFunction) {
 			for (Object argument : invocation.getArguments()) {
-				if (CoroutinesUtils.KOTLIN_CONTINUATION_CLASS.isAssignableFrom(argument.getClass())) {
+				if (argument != null && CoroutinesUtils.isContinuation(argument)) {
 					continuation = argument;
 					break;
 				}
@@ -1029,8 +1029,8 @@ protected void doStop() {
 		this.gatewayMap.values().forEach(MethodInvocationGateway::stop);
 	}
 
-	@SuppressWarnings("unchecked")
 	@Nullable
+	@SuppressWarnings("unchecked")
 	private <T> T convert(Object source, Class<T> expectedReturnType, @Nullable Object continuation) {
 		if (continuation != null) {
 			return CoroutinesUtils.monoAwaitSingleOrNull((Mono<T>) source, continuation);

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

@@ -24,6 +24,7 @@
 import org.springframework.beans.factory.BeanFactoryAware;
 import org.springframework.beans.factory.BeanInitializationException;
 import org.springframework.beans.factory.InitializingBean;
+import org.springframework.core.KotlinDetector;
 import org.springframework.integration.support.NullAwarePayloadArgumentResolver;
 import org.springframework.messaging.converter.MessageConverter;
 import org.springframework.messaging.handler.annotation.support.DefaultMessageHandlerMethodFactory;
@@ -98,7 +99,9 @@ private List<HandlerMethodArgumentResolver> buildArgumentResolvers(boolean listC
 			resolvers.add(new CollectionArgumentResolver(true));
 		}
 		resolvers.add(new MapArgumentResolver());
-		resolvers.add(new ContinuationHandlerMethodArgumentResolver());
+		if (KotlinDetector.isKotlinPresent()) {
+			resolvers.add(new ContinuationHandlerMethodArgumentResolver());
+		}
 
 		for (HandlerMethodArgumentResolver resolver : resolvers) {
 			if (resolver instanceof BeanFactoryAware) {

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -488,7 +488,7 @@ private Object processInternal(ParametersWrapper parameters) {
 
 	private synchronized void initialize() {
 		if (isProvidedMessageHandlerFactoryBean()) {
-			LOGGER.info("Overriding default instance of MessageHandlerMethodFactory with provided one.");
+			LOGGER.trace("Overriding default instance of MessageHandlerMethodFactory with provided one.");
 			this.messageHandlerMethodFactory =
 					getBeanFactory()
 							.getBean(

spring-integration-core/src/main/java/org/springframework/integration/util/CoroutinesUtils.java

@@ -19,7 +19,6 @@
 import org.springframework.core.KotlinDetector;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
-import org.springframework.util.ClassUtils;
 
 import reactor.core.publisher.Mono;
 
@@ -34,43 +33,20 @@
  */
 public final class CoroutinesUtils {
 
-	/**
-	 * The {@link kotlin.coroutines.Continuation} class object.
-	 */
-	@Nullable
-	public static final Class<?> KOTLIN_CONTINUATION_CLASS;
-
-	static {
-		if (KotlinDetector.isKotlinPresent()) {
-			Class<?> kotlinClass = null;
-			try {
-				kotlinClass = ClassUtils.forName("kotlin.coroutines.Continuation", ClassUtils.getDefaultClassLoader());
-			}
-			catch (ClassNotFoundException ex) {
-				//Ignore: assume no Kotlin in classpath
-			}
-			finally {
-				KOTLIN_CONTINUATION_CLASS = kotlinClass;
-			}
-		}
-		else {
-			KOTLIN_CONTINUATION_CLASS = null;
-		}
-	}
-
 	public static boolean isContinuation(Object candidate) {
 		return isContinuationType(candidate.getClass());
 	}
 
 	public static boolean isContinuationType(Class<?> candidate) {
-		return KOTLIN_CONTINUATION_CLASS != null && KOTLIN_CONTINUATION_CLASS.isAssignableFrom(candidate);
+		return KotlinDetector.isKotlinPresent() && kotlin.coroutines.Continuation.class.isAssignableFrom(candidate);
 	}
 
 	@Nullable
 	@SuppressWarnings("unchecked")
 	public static <T> T monoAwaitSingleOrNull(Mono<? extends T> source, Object continuation) {
-		Assert.notNull(KOTLIN_CONTINUATION_CLASS, "Kotlin Coroutines library is not present in classpath");
-		Assert.isAssignable(KOTLIN_CONTINUATION_CLASS, continuation.getClass());
+		Assert.state(isContinuation(continuation), () ->
+				"The 'continuation' must be an instance of 'kotlin.coroutines.Continuation', but it is: "
+						+ continuation.getClass());
 		return (T) kotlinx.coroutines.reactor.MonoKt.awaitSingleOrNull(
 				source, (kotlin.coroutines.Continuation<T>) continuation);
 	}