Writing the content of StringBuilder to a file without calling ToString()

StringBuilder.CopyTo.cs

public static class Utility
{
    /// <summary>
    /// Buffer-copy the specified StringBuilder contents into a text writer. 
    /// </summary>
    /// <param name="stringBuilder"></param>
    /// <param name="stringWriter"></param>
    /// <returns></returns>
    public static long CopyTo(this StringBuilder stringBuilder, TextWriter stringWriter)
    {
        // inspired from <https://stackoverflow.com/a/49778464/282105>
        // "Writing the content of StringBuilder to a file without calling ToString()"
        const int bufferSize = 10000;
        char[] buffer = new char[bufferSize];
        long total = 0L;

        for (int i = 0; i < stringBuilder.Length; i += bufferSize)
        {
            int count = Math.Min(bufferSize, stringBuilder.Length - i);
            stringBuilder.CopyTo(i, buffer, 0, count);
            stringWriter.Write(buffer, 0, count);
            total += count;
        }

        return total;
    }
}