code: public void reset() {
      checkReadOnly();
      if (state != READY && state != DONE) {
        throw new ResetException();
      }
      state = RESET;
      LIB.mdb_txn_reset(ptr);
    }
docs: Aborts this read-only transaction and resets the transaction handle so it
  can be reused upon calling {@link #renew()}.