This has been fixed for the next release. In order for it to work you would have to set the values to null instead of undefined. In the new config system, setting something to undefined will use the default value, setting it to null won't.
Because we believed having to set these to null every time you didn't want to send them was rather ugly, we have also added a new configuration on proxy called enablePagingParams. By configuring this to be false or calling proxy.setEnablePagingParams(false) (default is true to stay backwards compatible), none of the paging parameters will be sent with your request.