docs: public Assignment update(Border border) {
      Arrays.sort(cs);
      int j = 1;
      boolean found = (cs[0].core == border.core);
      for(int i = 1; i < cs.length; i++) {
        if(cs[i].core != cs[i - 1].core) {
          cs[j++] = cs[i];
        }
        found |= (cs[i].core == border.core);
      }
      if(found) {
        if(j == 1) {
          Border r = cs[0];
          cs = null; // Prevent further use
          return r;
        }
        if(j < cs.length) {
          cs = Arrays.copyOf(cs, j);
        }
        return this;
      }
      if(j + 1 != cs.length) {
        cs = Arrays.copyOf(cs, j + 1);
      }
      cs[j] = border;
      return this;
    }