Classes in nashorn "objects" package are loaded by a different loader. Wherever we use MethodHandleFactory ("MH") in findOwnMH, we can not use create method handle of private methods (because of different loader). It is better to use MethodHandles.publicLookup() to be sure for public methods - so that we don't pass these under 'no security' mode but fail under security manager. Wherever we create method handles on private methods, we could use MethodHandles API directly.