@Override
  public void toData(DataOutput out,
      SerializationContext context) throws IOException {
    super.toData(out, context);
    out.writeBoolean(cancelled);
    DataSerializer.writeObject(snapshot, out);
  }
Populates the collection of sub-region snapshots for the parentSnapShot with snapshots for the
regions given.

@param parentSnapShot RegionSubRegionSnapshot of a parent region
@param regions collection of sub-regions of the region represented by parentSnapShot
@param cache cache instance is used for to get the LogWriter instance to log exceptions if any
geode-core/src/main/java/org/apache/geode/internal/admin/remote/RegionSubRegionsSizeResponse.java