Path support for EXEC request is either not there (don't remember anymore ;-) but is at least incomplete:

• No path can be given for GET requests since everything is slurped in by arguments. It would be better to only consume the arguments required and then the rest as a path value to be applied to the operation return value.
• The Java Client doesn't support path for EXEC request

In principle it should be easily possible, since path gets applied on the return value of the request handler (the same way as the read handler).