docs: public boolean isSet(_Fields field) {
      if (field == null) {
        throw new java.lang.IllegalArgumentException();
      }
  
      switch (field) {
        case TX_STAMPS_START:
          return isSetTxStampsStart();
        case GC_STAMP:
          return isSetGcStamp();
      }
      throw new java.lang.IllegalStateException();
    }