DATACMNS-1197 - Polishing.

Some cleanups in KorlinReflectionUtils. Removed compiler warnings about nullability and raw types.

Original pull request: #254.

Author: odrotbohm

src/main/java/org/springframework/data/util/ReflectionUtils.java

@@ -23,7 +23,6 @@
 import kotlin.reflect.KProperty;
 import kotlin.reflect.KType;
 import kotlin.reflect.jvm.ReflectJvmMapping;
-import kotlin.reflect.jvm.internal.impl.load.kotlin.header.KotlinClassHeader;
 import kotlin.reflect.jvm.internal.impl.load.kotlin.header.KotlinClassHeader.Kind;
 import kotlin.reflect.jvm.internal.impl.load.kotlin.reflect.ReflectKotlinClass;
 import lombok.NonNull;
@@ -384,13 +383,7 @@ public static boolean isSupportedKotlinClass(Class<?> type) {
 
 		ReflectKotlinClass kotlinClass = ReflectKotlinClass.Factory.create(type);
 
-		if (kotlinClass == null) {
-			return false;
-		}
-
-		KotlinClassHeader classHeader = kotlinClass.getClassHeader();
-
-		return classHeader.getKind() == Kind.CLASS;
+		return kotlinClass == null ? false : kotlinClass.getClassHeader().getKind() == Kind.CLASS;
 	}
 
 	/**
@@ -428,19 +421,24 @@ static class KotlinReflectionUtils {
 		static boolean isNullable(MethodParameter parameter) {
 
 			Method method = parameter.getMethod();
+
+			if (method == null) {
+				throw new IllegalStateException(String.format("Cannot obtain method from parameter %s!", parameter));
+			}
+
 			KFunction<?> kotlinFunction = ReflectJvmMapping.getKotlinFunction(method);
 
 			if (kotlinFunction == null) {
 
 				// Fallback to own lookup because there's no public Kotlin API for that kind of lookup until
 				// https://youtrack.jetbrains.com/issue/KT-20768 gets resolved.
-				Optional<? extends KFunction> first = findKFunction(method);
-
-				kotlinFunction = first.orElseThrow(
-						() -> new IllegalArgumentException(String.format("Cannot resolve %s to a Kotlin function!", parameter)));
+				kotlinFunction = findKFunction(method)//
+						.orElseThrow(() -> new IllegalArgumentException(
+								String.format("Cannot resolve %s to a Kotlin function!", parameter)));
 			}
 
-			KType type = parameter.getParameterIndex() == -1 ? kotlinFunction.getReturnType()
+			KType type = parameter.getParameterIndex() == -1 //
+					? kotlinFunction.getReturnType() //
 					: kotlinFunction.getParameters().get(parameter.getParameterIndex() + 1).getType();
 
 			return type.isMarkedNullable();
@@ -452,26 +450,22 @@ static boolean isNullable(MethodParameter parameter) {
 		 * @param method the JVM {@link Method} to look up.
 		 * @return {@link Optional} wrapping a possibly existing {@link KFunction}.
 		 */
-		private static Optional<? extends KFunction> findKFunction(Method method) {
+		private static Optional<? extends KFunction<?>> findKFunction(Method method) {
 
 			KClass<?> kotlinClass = JvmClassMappingKt.getKotlinClass(method.getDeclaringClass());
 
 			return kotlinClass.getMembers() //
 					.stream() //
 					.flatMap(KotlinReflectionUtils::toKFunctionStream) //
-					.filter(it -> {
-
-						Method javaMethod = ReflectJvmMapping.getJavaMethod(it);
-						return javaMethod != null && javaMethod.equals(method);
-					}) //
+					.filter(it -> isSame(it, method)) //
 					.findFirst();
 		}
 
-		private static Stream<? extends KFunction> toKFunctionStream(KCallable<?> it) {
+		private static Stream<? extends KFunction<?>> toKFunctionStream(KCallable<?> it) {
 
 			if (it instanceof KMutableProperty<?>) {
 
-				KMutableProperty property = (KMutableProperty<?>) it;
+				KMutableProperty<?> property = (KMutableProperty<?>) it;
 				return Stream.of(property.getGetter(), property.getSetter());
 			}
 
@@ -487,5 +481,11 @@ private static Stream<? extends KFunction> toKFunctionStream(KCallable<?> it) {
 
 			return Stream.empty();
 		}
+
+		private static boolean isSame(KFunction<?> function, Method method) {
+
+			Method javaMethod = ReflectJvmMapping.getJavaMethod(function);
+			return javaMethod != null && javaMethod.equals(method);
+		}
 	}
 }