Support final @Configuration(proxyBeanMethods = false) classes

Closes gh-22869

spring-context/src/main/java/org/springframework/context/annotation/ConfigurationClass.java

@@ -211,15 +211,16 @@ final class ConfigurationClass {
 	}
 
 	public void validate(ProblemReporter problemReporter) {
-		// A configuration class may not be final (CGLIB limitation)
-		if (getMetadata().isAnnotated(Configuration.class.getName())) {
-			if (getMetadata().isFinal()) {
+		// A configuration class may not be final (CGLIB limitation) unless it declares proxyBeanMethods=false
+		String annotationName = Configuration.class.getName();
+		if (this.metadata.isAnnotated(annotationName) &&
+				(Boolean) this.metadata.getAnnotationAttributes(annotationName).get("proxyBeanMethods")) {
+			if (this.metadata.isFinal()) {
 				problemReporter.error(new FinalConfigurationProblem());
 			}
-		}
-
-		for (BeanMethod beanMethod : this.beanMethods) {
-			beanMethod.validate(problemReporter);
+			for (BeanMethod beanMethod : this.beanMethods) {
+				beanMethod.validate(problemReporter);
+			}
 		}
 	}
 

spring-context/src/test/kotlin/org/springframework/context/annotation/KotlinConfigurationClassTests.kt

@@ -0,0 +1,62 @@
+/*
+ * Copyright 2002-2019 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.context.annotation
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+import org.springframework.beans.factory.getBean
+import org.springframework.beans.factory.parsing.BeanDefinitionParsingException
+
+class KotlinConfigurationClassTests {
+
+	@Test(expected = BeanDefinitionParsingException::class)
+	fun `Final configuration with default proxyBeanMethods value`() {
+		AnnotationConfigApplicationContext(FinalConfigurationWithProxy::class.java)
+	}
+
+	@Test
+	fun `Final configuration with proxyBeanMethods set to false`() {
+		val context = AnnotationConfigApplicationContext(FinalConfigurationWithoutProxy::class.java)
+		val foo = context.getBean<Foo>()
+		assertEquals(foo, context.getBean<Bar>().foo)
+	}
+
+
+	@Configuration
+	class FinalConfigurationWithProxy {
+
+		@Bean
+		fun foo() = Foo()
+
+		@Bean
+		fun bar(foo: Foo) = Bar(foo)
+	}
+
+	@Configuration(proxyBeanMethods = false)
+	class FinalConfigurationWithoutProxy {
+
+		@Bean
+		fun foo() = Foo()
+
+		@Bean
+		fun bar(foo: Foo) = Bar(foo)
+	}
+
+	class Foo
+
+	class Bar(val foo: Foo)
+}