docs: public synchronized void rollbackToSavepoint() {
  
          if (isClosed) {
              return;
          }
  
          String name = (String) sessionContext.savepoints.getKey(0);
  
          database.txManager.rollbackSavepoint(this, 0);
  
          try {
              database.logger.writeToLog(this, getSavepointRollbackSQL(name));
          } catch (HsqlException e) {}
      }