code: public void sortByDocID() {
          Collections.sort(this, new Comparator<RevisionInternal>() {
              public int compare(RevisionInternal rev1, RevisionInternal rev2) {
                  return rev1.getDocID().compareTo(rev2.getDocID());
              }
          });
      }
docs: in CBL_Revision.m
  - (void) sortByDocID