src/java.base/share/classes/sun/misc/JavaLangAccess.java

@@ -27,10 +27,11 @@
 
 import java.lang.annotation.Annotation;
 import java.lang.reflect.Executable;
 import java.security.AccessControlContext;
 import java.util.Map;
+import java.util.function.Function;
 
 import sun.reflect.ConstantPool;
 import sun.reflect.annotation.AnnotationType;
 import sun.nio.ch.Interruptible;
 

@@ -78,10 +79,18 @@
      * Class object does not represent an enum type;
      * the result is uncloned, cached, and shared by all callers.
      */
     <E extends Enum<E>> E[] getEnumConstantsShared(Class<E> klass);
 
+    /**
+     * If given Class represents a generic class or interface, then the result of
+     * applying given function to the Class object is returned, otherwise null.
+     * The result is cached in per-Class map using identity of given key.
+     */
+    <D> D getGenericDerivative(Class<?> clazz, Object key,
+                               Function<Class<?>, ? extends D> function);
+
     /** Set thread's blocker field. */
     void blockedOn(Thread t, Interruptible b);
 
     /**
      * Registers a shutdown hook.