code: public int compare(BuildableItem lhs, BuildableItem rhs) {
          return compare(lhs.buildableStartMilliseconds,rhs.buildableStartMilliseconds);
      }
docs: Override this method to provide the ordering of the sort.
  
  <p>
  if lhs should be build before rhs, return a negative value. Or put another way, think of the comparison
  as a process of converting a {@link BuildableItem} into a number, then doing num(lhs)-num(rhs).
  
  <p>
  The default implementation does FIFO.