@Override
 protected void readTimePartitions(
     GribCollection.GroupHcs group, GribCollectionProto.Group proto) {
   List<TimeCoord> list = new ArrayList<TimeCoord>(proto.getTimeCoordUnionsCount());
   for (int i = 0; i < proto.getTimeCoordUnionsCount(); i++) {
     GribCollectionProto.TimeCoordUnion tpu = proto.getTimeCoordUnions(i);
     list.add(readTimePartition(tpu, i));
   }
   group.timeCoords = list;
 }