[N1QL] Json encoded creds is not recognized by query

Query accepts only form encoded creds parameter, it fails when using json encoding.

curl -H "Content-Type: application/json" -X POST http://127.0.0.1:8093/query/service -d '{ "statement" : "create primary index on default","creds": [

{"user":"default", "pass": ""}

] }'
{
"requestID": "0fd85fa1-242b-4a5e-b460-4557c241c8d9",
"errors": [
{
"code": 1070,
"msg": "creds has to be of type array of

{ user, pass }

"
}
],
"status": "fatal",
"metrics":

{ "elapsedTime": "152.899µs", "executionTime": "144.236µs", "resultCount": 0, "resultSize": 0, "errorCount": 1 }

}