SQL Developer is bringing the ability to define all the APEX Listener's REST abilities.  There's many advantages to adding this in.  The first and probably most important to me who typos and doesn't see it, is the ability to test the query or plsql before publishing it and getting a 500 error and not knowing why.

  This screenshot shows many other advantages of adding in.  The REST definition screens will have a fully functioning SQL Worksheet to test and tune the source of the REST call.  That means code insight, explain ,autotrace, sql tuning advisor, grids of data, and anything else.