code: public Operation asOperation(Clock clock) {
      Operation.Builder b = Operation.newBuilder();
      b.setImportance(Importance.LOW);
      Timestamp now = Timestamps.now(clock);
      b.setStartTime(now).setEndTime(now);
      if (!Strings.isNullOrEmpty(operationId)) {
        b.setOperationId(operationId);
      }
      if (!Strings.isNullOrEmpty(operationName)) {
        b.setOperationName(operationName);
      }
      String consumerId = getOperationConsumerId();
      if (!Strings.isNullOrEmpty(consumerId)) {
        b.setConsumerId(consumerId);
      }
      return b.build();
    }
docs: Returns the {@link Operation} instance corresponding to this instance.
  
  @param clock is used to determine the current timestamp
  
  @return a {@link Operation}