docs: protected QueryBuilder clear( boolean clearFirstQuery ) {
          source = new AllNodes();
          constraint = null;
          columns = new LinkedList<Column>();
          orderings = new LinkedList<Ordering>();
          limit = Limit.NONE;
          distinct = false;
          if (clearFirstQuery) {
              this.firstQuery = null;
              this.firstQuerySetOperation = null;
          }
          return this;
      }