The docs for $.Callbacks().has indicate that an argument is required

The documentation for $.Callbacks().has does not describe that the argument for the method is actually optional even though the source code for the method says otherwise[1].

I tried to add a suitable description to the method to indicate this. If it is not sufficient enough, I will go ahead and open an issue to update the docs instead.


[1] https://github.com/jquery/jquery/blob/master/src/callbacks.js#L145