GH-648 Fix Kotlin functions bootstrap

Resolves #648

spring-cloud-function-kotlin/pom.xml

@@ -42,6 +42,14 @@
 				<artifactId>kotlin-maven-plugin</artifactId>
 				<groupId>org.jetbrains.kotlin</groupId>
 				<version>1.4.21</version>
+				<configuration>
+					<args>
+						<arg>-Xjsr305=strict</arg>
+					</args>
+					<compilerPlugins>
+						<plugin>spring</plugin>
+					</compilerPlugins>
+				</configuration>
 				<executions>
 					<execution>
 						<id>compile</id>
@@ -68,6 +76,13 @@
 						</configuration>
 					</execution>
 				</executions>
+				<dependencies>
+					<dependency>
+						<groupId>org.jetbrains.kotlin</groupId>
+						<artifactId>kotlin-maven-allopen</artifactId>
+						<version>1.4.21</version>
+					</dependency>
+				</dependencies>
 			</plugin>
 			<plugin>
 				<groupId>org.apache.maven.plugins</groupId>

spring-cloud-function-kotlin/src/main/java/org/springframework/cloud/function/context/config/KotlinLambdaToFunctionAutoConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2021 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.
@@ -36,6 +36,7 @@ import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.BeanFactoryAware;
 import org.springframework.beans.factory.BeanNameAware;
 import org.springframework.beans.factory.FactoryBean;
+import org.springframework.beans.factory.annotation.AnnotatedBeanDefinition;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
@@ -62,7 +63,6 @@ public class KotlinLambdaToFunctionAutoConfiguration {
 
 	protected final Log logger = LogFactory.getLog(getClass());
 
-
 	/**
 	 * Will transform all discovered Kotlin's Function lambdas to java
 	 * Supplier, Function and Consumer, retaining the original Kotlin type
@@ -71,7 +71,7 @@ public class KotlinLambdaToFunctionAutoConfiguration {
 	 * @return the bean factory post processor
 	 */
 	@Bean
-	public BeanFactoryPostProcessor kotlinToFunctionTransformer() {
+	public BeanFactoryPostProcessor kotlinToFunctionTransformerOld() {
 		return new BeanFactoryPostProcessor() {
 
 			@Override
@@ -82,14 +82,17 @@ public class KotlinLambdaToFunctionAutoConfiguration {
 				for (String beanDefinitionName : beanDefinitionNames) {
 					BeanDefinition beanDefinition = beanFactory.getBeanDefinition(beanDefinitionName);
 
-					ResolvableType rt = beanDefinition.getResolvableType();
-					if (rt.getType().getTypeName().startsWith("kotlin.jvm.functions.Function")) {
-						RootBeanDefinition cbd = new RootBeanDefinition(KotlinFunctionWrapper.class);
-						ConstructorArgumentValues ca = new ConstructorArgumentValues();
-						ca.addGenericArgumentValue(beanDefinition);
-						cbd.setConstructorArgumentValues(ca);
-						((BeanDefinitionRegistry) beanFactory).registerBeanDefinition(beanDefinitionName + FunctionRegistration.REGISTRATION_NAME_SUFFIX, cbd);
+					if (beanDefinition instanceof AnnotatedBeanDefinition && ((AnnotatedBeanDefinition) beanDefinition).getFactoryMethodMetadata() != null) {
+						String typeName = ((AnnotatedBeanDefinition) beanDefinition).getFactoryMethodMetadata().getReturnTypeName();
+						if (typeName.startsWith("kotlin.jvm.functions.Function")) {
+							RootBeanDefinition cbd = new RootBeanDefinition(KotlinFunctionWrapper.class);
+							ConstructorArgumentValues ca = new ConstructorArgumentValues();
+							ca.addGenericArgumentValue(beanDefinition);
+							cbd.setConstructorArgumentValues(ca);
+							((BeanDefinitionRegistry) beanFactory).registerBeanDefinition(beanDefinitionName + FunctionRegistration.REGISTRATION_NAME_SUFFIX, cbd);
+						}
 					}
+
 				}
 			}
 		};

spring-cloud-function-kotlin/src/test/java/org/springframework/cloud/function/kotlin/ContextFunctionCatalogAutoConfigurationKotlinTests.java

@@ -76,6 +76,13 @@ public class ContextFunctionCatalogAutoConfigurationKotlinTests {
 		assertThat(functionType.getRawType().getTypeName()).isEqualTo(Supplier.class.getName());
 		assertThat(functionType.getActualTypeArguments().length).isEqualTo(1);
 		assertThat(functionType.getActualTypeArguments()[0].getTypeName()).isEqualTo(String.class.getName());
+
+		function = this.context.getBean("kotlinPojoFunction");
+		functionType = (ParameterizedType) FunctionTypeUtils.discoverFunctionType(function, "kotlinPojoFunction", this.context);
+		assertThat(functionType.getRawType().getTypeName()).isEqualTo(Function.class.getName());
+		assertThat(functionType.getActualTypeArguments().length).isEqualTo(2);
+		assertThat(functionType.getActualTypeArguments()[0].getTypeName()).isEqualTo(Person.class.getName());
+		assertThat(functionType.getActualTypeArguments()[1].getTypeName()).isEqualTo(String.class.getName());
 	}
 
 	@Test

spring-cloud-function-kotlin/src/test/kotlin/org/springframework/cloud/function/kotlin/KotlinLambdasConfiguration.kt

@@ -27,24 +27,29 @@ import java.util.function.Function
  */
 @EnableAutoConfiguration
 @Configuration
-open class KotlinLambdasConfiguration {
+class KotlinLambdasConfiguration {
 	@Bean
-	open fun kotlinFunction(): (String) -> String {
+	fun kotlinFunction(): (String) -> String {
 		return { it.toUpperCase() }
 	}
+	
+	@Bean
+	fun kotlinPojoFunction(): (Person) -> String {
+		return { it.name.toString()}
+	}
 
 	@Bean
-	open fun kotlinConsumer(): (String) -> Unit {
+	fun kotlinConsumer(): (String) -> Unit {
 		return { println(it) }
 	}
 
 	@Bean
-	open fun kotlinSupplier(): () -> String {
+	fun kotlinSupplier(): () -> String {
 		return { "Hello" }
 	}
 
 	@Bean
-	open fun javaFunction(): Function<String, String> {
+	fun javaFunction(): Function<String, String> {
 		return Function { x -> x }
 	}
 }

spring-cloud-function-kotlin/src/test/kotlin/org/springframework/cloud/function/kotlin/Person.kt

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2012-2021 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.cloud.function.kotlin
+
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration
+import org.springframework.context.annotation.Bean
+import org.springframework.context.annotation.Configuration
+import java.util.function.Function
+
+/**
+ * @author Oleg Zhurakousky
+ *
+ */
+class Person {
+	
+	var name:String? = null;
+	
+	
+}