private boolean isFilled(int x, int y) {
    if (filledRanges == null) {
      return false;
    }
    var filledCol = filledRanges.get(x);
    if (filledCol == null) {
      return false;
    }
    return filledCol.contains(y);
  }
Splits an entire vertical X column of edge segments into Y rows that form (X, Y) tile coordinates at this zoom
level, stores the result in {@link #tileContents} and returns the Y ranges of filled tile coordinates if this is a
polygon.
planetiler-core/src/main/java/com/onthegomap/planetiler/render/TiledGeometry.java