* @param b
* the other pack.
*/
public int compareTo(DfsPackDescription b) {
// Cluster by PackSource, pushing UNREACHABLE_GARBAGE to the end.
PackSource as = getPackSource();
PackSource bs = b.getPackSource();
if (as != null && bs != null) {
int cmp = as.category - bs.category;
if (cmp != 0)
return cmp;
}