C# - XML Encoding eines XmlDocument ändern

/// <summary>
/// Changes the XML encoding.
/// </summary>
/// <param name="xmlDoc">The XmlDocument.</param>
/// <param name="newEncoding">The new encoding.</param>
/// <returns></returns>
private XmlDocument ChangeXmlEncoding(XmlDocument xmlDoc, string newEncoding)
{
    if (xmlDoc.FirstChild.NodeType == XmlNodeType.XmlDeclaration)
    {
        XmlDeclaration xmlDeclaration = (XmlDeclaration)xmlDoc.FirstChild;
        xmlDeclaration.Encoding = newEncoding;
    }
    return xmlDoc;
}