docs: public int nextSetBit(final int i) {
      int x = i >> 6; // signed i / 64
      long w = bitmap.get(x);
      w >>>= i;
      if (w != 0) {
        return i + numberOfTrailingZeros(w);
      }
      // for speed, replaced bitmap.limit() with hardcoded MAX_CAPACITY / 64
      for (++x; x < MAX_CAPACITY / 64; ++x) {
        long X = bitmap.get(x);
        if (X != 0) {
          return x * 64 + numberOfTrailingZeros(X);
        }
      }
      return -1;
    }