Fix webflux-kotlin sample and add KotlinRuntimeHints

Author: sdeleuze

3rd-party-hints/src/main/java/org/springframework/aot/thirdpartyhints/KotlinRuntimeHints.java

@@ -0,0 +1,37 @@
+package org.springframework.aot.thirdpartyhints;
+
+import org.springframework.aot.hint.MemberCategory;
+import org.springframework.aot.hint.ReflectionHints;
+import org.springframework.aot.hint.RuntimeHints;
+import org.springframework.aot.hint.RuntimeHintsRegistrar;
+import org.springframework.aot.hint.TypeReference;
+import org.springframework.core.KotlinDetector;
+
+/**
+ * @author Sebastien Deleuze
+ */
+// TODO: Contribute these hints to graalvm-reachability-metadata repository
+public class KotlinRuntimeHints implements RuntimeHintsRegistrar {
+
+
+	@Override
+	public void registerHints(RuntimeHints hints, ClassLoader classLoader) {
+		if (!KotlinDetector.isKotlinReflectPresent()) {
+			return;
+		}
+		hints.resources()
+				.registerPattern("META-INF/*.kotlin_module")
+				.registerPattern("*.kotlin_builtins");
+
+		ReflectionHints reflectionHints = hints.reflection();
+
+		reflectionHints.registerType(TypeReference.of("kotlin.reflect.full.KClasses"),
+				builder -> {});
+		reflectionHints.registerType(TypeReference.of("kotlin.Metadata"),
+				builder ->builder.withMembers(MemberCategory.INVOKE_DECLARED_METHODS));
+		reflectionHints.registerType(TypeReference.of("kotlin.reflect.jvm.internal.ReflectionFactoryImpl"),
+				builder -> builder.withMembers(MemberCategory.INVOKE_PUBLIC_CONSTRUCTORS));
+		reflectionHints.registerType(TypeReference.of("kotlin.reflect.jvm.internal.impl.resolve.scopes.DescriptorKindFilter"),
+				builder -> builder.withMembers(MemberCategory.DECLARED_FIELDS));
+	}
+}

samples/webflux-kotlin/src/main/kotlin/com/example/webflux/WebfluxApplication.kt

@@ -1,12 +1,13 @@
 package com.example.webflux
 
+import org.springframework.aot.thirdpartyhints.KotlinRuntimeHints
 import org.springframework.aot.thirdpartyhints.NettyRuntimeHints
 import org.springframework.boot.autoconfigure.SpringBootApplication
 import org.springframework.boot.runApplication
 import org.springframework.context.annotation.ImportRuntimeHints
 
 @SpringBootApplication
-@ImportRuntimeHints(NettyRuntimeHints::class)
+@ImportRuntimeHints(NettyRuntimeHints::class, KotlinRuntimeHints::class)
 class WebfluxApplication
 
 fun main(args: Array<String>) {