public boolean addSubRegion(RegionSubRegionSnapshot snap) {
    if (subRegionSnapshots.contains(snap)) {
      return true;
    }

    if (subRegionSnapshots.add(snap)) {
      snap.setParent(this);
      return true;
    }

    return false;
  }
add the snapshot of sub region

@param snap snapshot of sub region
@return true if operation is successful
geode-core/src/main/java/org/apache/geode/admin/RegionSubRegionSnapshot.java