getSingleContact
@MessageMapping(value = ["get.single"] )
Get a number request/response RSocket API. Takes as argument a number as String encoded in ProtoBuf format in payload. In metadata takes the client path as String.
Returns a HubPayload encoded in ProtoBuf format. In case the operation was successful the HubPayload contains data with the matched contact. Else it contains error with the corresponding code. If there is not any matching accounts it returns code 404 and if the input is not a valid Msisdn it returns code 400.