void collectReferencedChunks(Set<Integer> target){
  target.add(DataUtils.getPageChunkId(pos));
  for (  long p : children) {
    target.add(DataUtils.getPageChunkId(p));
  }
}

void collectReferencedChunks ( Set < Integer > target ) { target . add ( DataUtils . getPageChunkId ( pos ) ) ; for ( long p : children ) { target . add ( DataUtils . getPageChunkId ( p ) ) ; } }
collect the set of chunks referenced directly by this page .
