Fixed #23287 -- Updated error message for classonlymethod decorator.

class classonlymethod(classmethod):

    def __get__(self, instance, owner):

        if instance is not None:

            raise AttributeError("This method is available only on the view class.")

            raise AttributeError("This method is available only on the class, not on instances.")

        return super(classonlymethod, self).__get__(instance, owner)