1 files changed, 39 insertions, 0 deletions
diff --git a/bundle-plugin/src/main/java/com/yahoo/container/plugin/util/JdkPackages.java b/bundle-plugin/src/main/java/com/yahoo/container/plugin/util/JdkPackages.java
new file mode 100644
index 00000000000..0786272bc70
--- /dev/null
+++ b/bundle-plugin/src/main/java/com/yahoo/container/plugin/util/JdkPackages.java
@@ -0,0 +1,39 @@
+package com.yahoo.container.plugin.util;
+
+import java.net.URL;
+
+/**
+ * @author gjoranv
+ */
+public class JdkPackages {
+
+    /**
+     * Returns a boolean indicating (via best effort) if the given package is part of the JDK.
+     */
+    public static boolean isJdkPackage(String pkg) {
+        return hasJdkExclusivePrefix(pkg)
+                || isResourceInPlatformClassLoader(pkg); // TODO: must be a class, not a package, due to module encapsulation
+    }
+
+    private static boolean isResourceInPlatformClassLoader(String klass) {
+        String klassAsPath = klass.replaceAll("\\.", "/") + ".class";
+        URL resource = getPlatformClassLoader().getResource(klassAsPath);
+        return !(resource == null);
+    }
+
+    private static ClassLoader getPlatformClassLoader() {
+        ClassLoader platform = JdkPackages.class.getClassLoader().getParent();
+
+        // Will fail upon changes in classloader hierarchy between JDK versions
+        assert (platform.getName().equals("platform"));
+
+        return platform;
+    }
+
+    private static boolean hasJdkExclusivePrefix(String pkg) {
+        return pkg.startsWith("java.")
+                || pkg.startsWith("sun.");
+    }
+
+}
+