public static List<VectorTile.Feature> mergeMultiPolygon(List<VectorTile.Feature> features) {
    return mergeGeometries(features, GeometryType.POLYGON);
  }
Merges polygons with the same attributes into multipolygons.
<p>
NOTE: This does not attempt to combine overlapping geometries, see {@link #mergeOverlappingPolygons(List, double)}
or {@link #mergeNearbyPolygons(List, double, double, double, double)} for that.
planetiler-core/src/main/java/com/onthegomap/planetiler/FeatureMerge.java