SerializableTypeWrapper detects Graal through system property as well

Issue: SPR-17136

Author: jhoeller

spring-core/src/main/java/org/springframework/core/DefaultParameterNameDiscoverer.java

@@ -38,12 +38,8 @@
  */
 public class DefaultParameterNameDiscoverer extends PrioritizedParameterNameDiscoverer {
 
-	// See https://github.com/oracle/graal/blob/master/sdk/src/org.graalvm.nativeimage/src/org/graalvm/nativeimage/ImageInfo.java
-	private static final boolean inImageCode = (System.getProperty("org.graalvm.nativeimage.imagecode") != null);
-
-
 	public DefaultParameterNameDiscoverer() {
-		if (!inImageCode) {
+		if (!GraalDetector.inImageCode()) {
 			if (KotlinDetector.isKotlinReflectPresent()) {
 				addDiscoverer(new KotlinReflectionParameterNameDiscoverer());
 			}

spring-core/src/main/java/org/springframework/core/GraalDetector.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2002-2018 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
+ *
+ *      http://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.core;
+
+/**
+ * A common delegate for detecting a GraalVM native image environment.
+ *
+ * @author Juergen Hoeller
+ * @author Sebastien Deleuze
+ * @since 5.1
+ */
+abstract class GraalDetector {
+
+	// See https://github.com/oracle/graal/blob/master/sdk/src/org.graalvm.nativeimage/src/org/graalvm/nativeimage/ImageInfo.java
+	private static final boolean imageCode = (System.getProperty("org.graalvm.nativeimage.imagecode") != null);
+
+
+	/**
+	 * Return whether this runtime environment lives within a native image.
+	 */
+	public static boolean inImageCode() {
+		return imageCode;
+	}
+
+}

spring-core/src/main/java/org/springframework/core/SerializableTypeWrapper.java

@@ -108,7 +108,7 @@ static Type forTypeProvider(TypeProvider provider) {
 			// No serializable type wrapping necessary (e.g. for java.lang.Class)
 			return providedType;
 		}
-		if (!Serializable.class.isAssignableFrom(Class.class)) {
+		if (GraalDetector.inImageCode() || !Serializable.class.isAssignableFrom(Class.class)) {
 			// Let's skip any wrapping attempts if types are generally not serializable in
 			// the current runtime environment (even java.lang.Class itself, e.g. on Graal)
 			return providedType;