code: public static synchronized <T> IExpectationSetters<T> expectPrivate(Object instance, String methodName,
                                                                          Object... arguments) throws Exception {
          if (instance == null) {
              throw new IllegalArgumentException("Instance or class cannot be null.");
          }
  
          return expectPrivate(instance, methodName, Whitebox.getType(instance), arguments);
      }
docs: Used to specify expectations on methods using the method name. Works on
  for example private or package private methods.