docs: private void growBaseBuffer() {
      final int oldSize = combinedBuffer_.length;
      assert oldSize < (2 * k_);
      final double[] baseBuffer = combinedBuffer_;
      final int newSize = 2 * Math.max(Math.min(k_, oldSize), DoublesSketch.MIN_K);
      combinedBuffer_ = Arrays.copyOf(baseBuffer, newSize);
    }