code: private synchronized boolean markIsTransaction(String channelId, String uuid, boolean isTransaction) {
          if (this.isTransaction == null) {
              return false;
          }
  
          String key = getTxKey(channelId, uuid);
          this.isTransaction.put(key, isTransaction);
          return true;
      }
docs: Marks a CHANNELID+UUID as either a transaction or a query
  
  @param uuid          ID to be marked
  @param isTransaction true for transaction, false for query
  @return whether or not the UUID was successfully marked