GH-685 Update Kotlin documentation

Add test for collections

polishing

docs/src/main/asciidoc/spring-cloud-function.adoc

@@ -467,7 +467,7 @@ The above represents Kotlin lambdas configured as Spring beans. The signature of
 While mechanics of Kotlin-to-Java mapping are outside of the scope of this documentation, it is important to understand that the
 same rules for signature transformation outlined in "Java 8 function support" section are applied here as well.
 
-To enable Kotlin support all you need is to add `spring-cloud-function-kotlin` module to your classpath which contains the appropriate
+To enable Kotlin support all you need is to add Kotlin SDK libraries on the classpath which will trigger appropriate
 autoconfiguration and supporting classes.
 
 === Function Component Scan

pom.xml

@@ -51,8 +51,8 @@
 		<module>spring-cloud-function-samples</module>
 		<module>spring-cloud-function-deployer</module>
 		<module>spring-cloud-function-adapters</module>
-		<module>spring-cloud-function-kotlin</module>
 		<module>spring-cloud-function-rsocket</module>
+		<module>spring-cloud-function-kotlin</module>
 		<module>docs</module>
 	</modules>
 

spring-cloud-function-kotlin/README.adoc

@@ -0,0 +1,4 @@
+!!! INTERNAL !!!
+
+Contains only Kotlin tests. 
+Since version 3.1.3, user's should not be declaring explicit dependency on this module.

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

@@ -33,6 +33,7 @@ import org.springframework.cloud.function.context.catalog.SimpleFunctionRegistry
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.support.GenericApplicationContext;
+import org.springframework.messaging.support.MessageBuilder;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -83,6 +84,30 @@ public class ContextFunctionCatalogAutoConfigurationKotlinTests {
 		assertThat(functionType.getActualTypeArguments().length).isEqualTo(2);
 		assertThat(functionType.getActualTypeArguments()[0].getTypeName()).isEqualTo(Person.class.getName());
 		assertThat(functionType.getActualTypeArguments()[1].getTypeName()).isEqualTo(String.class.getName());
+
+
+		function = this.context.getBean("kotlinListPojoFunction");
+		functionType = (ParameterizedType) FunctionTypeUtils.discoverFunctionType(function, "kotlinListPojoFunction", this.context);
+		assertThat(functionType.getRawType().getTypeName()).isEqualTo(Function.class.getName());
+		assertThat(functionType.getActualTypeArguments().length).isEqualTo(2);
+		assertThat(functionType.getActualTypeArguments()[0].getTypeName()).isEqualTo("java.util.List<org.springframework.cloud.function.kotlin.Person>");
+		assertThat(functionType.getActualTypeArguments()[1].getTypeName()).isEqualTo(String.class.getName());
+	}
+
+	@Test
+	public void testWithComplexTypesAndRouting() {
+		create(new Class[] { KotlinLambdasConfiguration.class,
+				SimpleConfiguration.class });
+
+		FunctionInvocationWrapper function = this.catalog.lookup("kotlinListPojoFunction");
+		String result = (String) function.apply("[{\"name\":\"Ricky\"}]");
+		assertThat(result).isEqualTo("List of: Ricky");
+
+		function = this.catalog.lookup(Function.class, "functionRouter");
+		result = (String) function.apply(MessageBuilder.withPayload("[{\"name\":\"Ricky\"}]")
+				.setHeader("spring.cloud.function.definition", "kotlinListPojoFunction").build());
+		assertThat(result).isEqualTo("List of: Ricky");
+
 	}
 
 	@Test

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

@@ -20,6 +20,7 @@ import org.springframework.boot.autoconfigure.EnableAutoConfiguration
 import org.springframework.context.annotation.Bean
 import org.springframework.context.annotation.Configuration
 import java.util.function.Function
+import java.util.List
 
 /**
  * @author Oleg Zhurakousky
@@ -37,6 +38,13 @@ class KotlinLambdasConfiguration {
 	fun kotlinPojoFunction(): (Person) -> String {
 		return { it.name.toString()}
 	}
+	
+	@Bean
+	fun kotlinListPojoFunction(): (List<Person>) -> String {
+		return {
+			"List of: " + it.get(0).name
+		}
+	}
 
 	@Bean
 	fun kotlinConsumer(): (String) -> Unit {