Add support for Kotlin Coroutines

Kotlin Coroutines are now supported but require additional
reflection entries due to how Coroutines generates bytecode
with an `Object` return type, see
spring-projects/spring-framework#21546
for a potential future fix.

Closes gh-409

Author: sdeleuze

spring-native-configuration/pom.xml

@@ -328,6 +328,11 @@
             <artifactId>lettuce-core</artifactId>
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.module</groupId>
+            <artifactId>jackson-module-kotlin</artifactId>
+            <scope>provided</scope>
+        </dependency>
 
         <dependency>
             <groupId>junit</groupId>

spring-native-configuration/src/main/java/kotlin/KotlinHints.java

@@ -1,31 +1,50 @@
 package kotlin;
 
-import org.springframework.nativex.type.NativeConfiguration;
+import org.springframework.nativex.hint.AccessBits;
 import org.springframework.nativex.hint.NativeHint;
 import org.springframework.nativex.hint.ResourcesInfo;
 import org.springframework.nativex.hint.TypeInfo;
+import org.springframework.nativex.type.NativeConfiguration;
 
+import static org.springframework.nativex.hint.AccessBits.*;
 import static org.springframework.nativex.hint.AccessBits.DECLARED_CONSTRUCTORS;
 import static org.springframework.nativex.hint.AccessBits.DECLARED_FIELDS;
 import static org.springframework.nativex.hint.AccessBits.DECLARED_METHODS;
 import static org.springframework.nativex.hint.AccessBits.PUBLIC_METHODS;
 
-@NativeHint(
-		trigger=kotlin.Unit.class,
+@NativeHint(trigger = kotlin.Unit.class,
 		resources = {
 				@ResourcesInfo(patterns= {
 						"META-INF/.*.kotlin_module$",
 						".*.kotlin_builtins",
 						"META-INF/services/.*"
 				})
 		}, types = {
-				@TypeInfo(types = kotlin.reflect.jvm.internal.ReflectionFactoryImpl.class, access = DECLARED_CONSTRUCTORS),
 				@TypeInfo(types = kotlin.KotlinVersion.class, access = PUBLIC_METHODS | DECLARED_FIELDS | DECLARED_METHODS | DECLARED_CONSTRUCTORS),
 				@TypeInfo(typeNames = {
 						"kotlin.KotlinVersion[]",
 						"kotlin.KotlinVersion$Companion",
 						"kotlin.KotlinVersion$Companion[]"
 				})
 })
+@NativeHint(trigger = kotlin.reflect.full.KClasses.class,
+	types = {
+		@TypeInfo(types = kotlin.reflect.full.KClasses.class, access = CLASS),
+		@TypeInfo(types = kotlin.Metadata.class, access = DECLARED_METHODS),
+		@TypeInfo(types = kotlin.reflect.jvm.internal.ReflectionFactoryImpl.class, access = DECLARED_CONSTRUCTORS),
+		@TypeInfo(types = kotlin.reflect.jvm.internal.impl.resolve.scopes.DescriptorKindFilter.class, access = DECLARED_FIELDS)
+	})
+@NativeHint(trigger = kotlin.coroutines.Continuation.class,
+		types = @TypeInfo(types = kotlin.coroutines.Continuation.class, typeNames = "kotlin.coroutines.Continuation[]", access = LOAD_AND_CONSTRUCT_AND_PUBLIC_METHODS))
+@NativeHint(trigger = com.fasterxml.jackson.module.kotlin.KotlinModule.class,
+		types = {
+			@TypeInfo(types = com.fasterxml.jackson.module.kotlin.KotlinModule.class),
+			@TypeInfo(typeNames = {
+					"com.fasterxml.jackson.module.kotlin.KotlinModule$Builder",
+					"com.fasterxml.jackson.module.kotlin.SingletonSupport",
+					"java.lang.String"
+			}, access = CLASS)
+		})
+
 public class KotlinHints implements NativeConfiguration {
 }

spring-native-configuration/src/main/java/org/springframework/SpringFrameworkHints.java

@@ -59,7 +59,8 @@
 				org.springframework.web.socket.sockjs.transport.TransportHandlingSockJsService.class,
 				org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.class,
 				org.springframework.core.ReactiveAdapterRegistry.class,
-				org.springframework.core.NativeDetector.class
+				org.springframework.core.NativeDetector.class,
+				org.springframework.core.KotlinDetector.class
 		}, typeNames = {
 				"org.springframework.aot.StaticSpringFactories",
 				"org.springframework.aop.Advisor$1",

spring-native-docs/src/main/asciidoc/support.adoc

@@ -12,6 +12,10 @@ Java 8, Java 11 and Kotlin 1.3+ are supported.
 Be aware that Java 11 native images are currently impacted by a transient footprint issue that may lead
 (or not) to bigger images due to https://github.com/oracle/graal/issues/3163[oracle/graal#3163].
 
+Kotlin Coroutines are supported but require additional reflection entries due to how Coroutines generates
+bytecode with an `Object` return type, see https://github.com/spring-projects/spring-framework/issues/21546[this related issue]
+for a potential future fix.
+
 === Spring Boot
 
 IMPORTANT: `spring-native` {version} is designed to be used with Spring Boot {boot-version}.

spring-native-samples/webflux-kotlin/.mvn/wrapper/maven-wrapper.jar

@@ -0,0 +1 @@
+distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.6.3/apache-maven-3.6.3-bin.zip

spring-native-samples/webflux-kotlin/.mvn/wrapper/maven-wrapper.properties

@@ -0,0 +1,13 @@
+Spring Boot project with Spring WebFlux, Coroutines, Netty and Jackson.
+
+To build and run the native application packaged in a lightweight container:
+```
+mvn spring-boot:build-image
+docker-compose up
+```
+
+And then go to [http://localhost:8080/](http://localhost:8080/).
+
+As an alternative, you can use `build.sh` (with a local GraalVM installation or combined with
+`run-dev-container.sh` at the root of `spring-native` project). See also the related issue
+[Take advantage of Paketo dev-oriented images](https://github.com/spring-projects-experimental/spring-native/issues/227).

spring-native-samples/webflux-kotlin/README.md

@@ -0,0 +1,3 @@
+#!/usr/bin/env bash
+
+${PWD%/*samples/*}/scripts/compileWithMaven.sh && ${PWD%/*samples/*}/scripts/test.sh

spring-native-samples/webflux-kotlin/build.sh

@@ -0,0 +1,6 @@
+version: '3.1'
+services:
+  webmvc-tomcat:
+    image: webflux-kotlin:0.0.1-SNAPSHOT
+    ports:
+      - "8080:8080"