private static void insert(final int mapY, final int mustBePlain, final int... emptyOrPlain) {
   final short patchId = PartitionPatch.getPatchIdFromMapCoord(1, mapY);
   BorderHelper.BORDER_PATCHES.put(mustBePlain, patchId);
   for (final int optional : emptyOrPlain) {
     insert(mapY, mustBePlain | optional, new int[0]);
     insert(mapY, mustBePlain | optional, allExcept(emptyOrPlain, optional));
   }
 }