code: public List<Point> getMazePoints() {
          List<Point> points = new ArrayList<Point>();
          for (int row = 0; row < this.rows; row++) {
              for (int column = 0; column < this.columns; column++) {
                  points.add(new Point(column, row));
              }
          }
          return points;
      }
docs: Return all tiles (i,j) of the maze
  
  @return List of points, from (0,0) to (m,n).