code: public static Collection<Integer> ofUnsetBits(long i) {
      	final Collection<Integer> c = new LinkedList<Integer>();
          int k = 0;
          while (i != 0) {
              if ((i & 1L) == 0) {
                  c.add(k);
              }
              k++;
              i >>>= 1;
          }
          return c;
      }
docs: Get the {@link Collection} of unset (0) bits inside a word or long word
  @param i
  @return
  The not null {@link Collection} of the indexes of set bits.
  The {@link Collection} implementation is an {@link LinkedList}.