Not sureif you ever found a solution, but you may want to throw questions like these into the resteasy forum.
Anyways, you can use @DefaultValue for optional parameters. I believe the spec is a first-match behavior (find the first method that can accept these arguments and continue). As a result, especially for query params, you should define a larger method to accept all params and give them default values.
I figured this once I read the spec and did such. Thanks for the response.