public static List<VectorTile.Feature> mergeMultiLineString(List<VectorTile.Feature> features) {
    return mergeGeometries(features, GeometryType.LINE);
  }
Merges linestrings with the same attributes into multilinestrings.
<p>
NOTE: This does not attempt to connect linestrings that intersect at endpoints, see
{@link #mergeLineStrings(List, double, double, double, boolean)} for that. Also, this removes extra detail that was
preserved to improve connected-linestring merging, so you should only use one or the other.
planetiler-core/src/main/java/com/onthegomap/planetiler/FeatureMerge.java