code: private List<Point2D> merge(final List<Point2D> one, final List<Point2D> two) {
          final Set<Point2D> oneSet = new HashSet<Point2D>(one);
          for (Point2D item : two) {
              if (!oneSet.contains(item)) {
                  one.add(item);
              }
          }
          return one;
      }
docs: Merges two lists together.
  
  @param one first list
  @param two second list
  @return merged lists