/** Return the next possible capacity, counting from the current buffers' size. */
    protected int nextCapacity(int current) {
      assert current > 0 && Long.bitCount(current) == 1 : "Capacity must be a power of two.";
      assert ((current << 1) > 0) : "Maximum capacity exceeded (" + (0x80000000 >>> 1) + ").";

      if (current < MIN_CAPACITY / 2) current = MIN_CAPACITY / 2;
      return current << 1;
    }