code: public Object unmarshalResult(Object respObj) throws RpcException {
          if (returns == null) {
              if (respObj != null) {
                  throw new IllegalArgumentException("Function " + name +
                                                     " is a notification and should not have a result");
              }
          }
          return returns.getTypeConverter().unmarshal(respObj);
      }
docs: Unmarshals respObj into its Java representation
  
  @throws RpcException if respObj does not match IDL type validation