docs: public DoubleIntIndex getTransactionIDList() {
  
          writeLock.lock();
  
          try {
              DoubleIntIndex lookup = new DoubleIntIndex(10, false);
  
              lookup.setKeysSearchTarget();
  
              Iterator it = this.rowActionMap.keySet().iterator();
  
              for (; it.hasNext(); ) {
                  lookup.addUnique(it.nextInt(), 0);
              }
  
              return lookup;
          } finally {
              writeLock.unlock();
          }
      }