named parameters cannot be found in JSON requests

The way the JSON request is parsed, named parameters "keys" are not stripped of their $ prefix, contrary to what is done for Http parsing here https://github.com/couchbaselabs/query/blob/master/server/http/service_request.go#L473

(see JSON named parameters parsing here: https://github.com/couchbaselabs/query/blob/master/server/http/service_request.go#L626)

Since named parameters are detected by noticing a $ prefix in the JSON request body, this can't be worked around by just not prefixing.

Possible workarounds at the moment are using positional parameters or using http url-form-encoded request mode...