public static MessageType valueOf(int value) {
        switch (value) {
          case 0: return ExecutionStarting;
          case 1: return SpecExecutionStarting;
          case 2: return SpecExecutionEnding;
          case 3: return ScenarioExecutionStarting;
          case 4: return ScenarioExecutionEnding;
          case 5: return ExecuteStep;
          case 6: return ExecuteStepResponse;
          case 7: return ExecutionEnding;
          case 8: return StepValidateRequest;
          case 9: return StepValidateResponse;
          case 10: return ExecutionStatusResponse;
          default: return null;
        }
      }