private static long longPair(int a, int b) {
    return (((long) a) << 32L) | (b & LOWER_32_BIT_MASK);
  }
Returns a copy of {@code geom} with coordinates rounded to {@code #tilePrecision} and fixes any polygon
self-intersections or overlaps that may have caused.

@throws GeometryException if an unrecoverable robustness exception prevents us from fixing the geometry
planetiler-core/src/main/java/com/onthegomap/planetiler/geo/GeoUtils.java