正确设置XmlSerializer选项

我的XmlSerializer代码输出的Xml比我需要的要详细得多，我如何正确控制输出设置?这是代码:

var stream = new MemoryStream();
var xmlSerializer = new XmlSerializer(objectToSerialize.GetType());            
xmlSerializer.Serialize(stream, objectToSerialize);
string xml = encoding != null ? encoding.GetString(stream.ToArray()) 
                              : Encoding.Default.GetString(stream.ToArray());

输出如下所示:

<?xml version="1.0"?>
<ArrayOfProduct xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Product>
    <Id>1</Id>
    <ProductCode>A</ProductCode>
    <ProductDescription>Product A</ProductDescription>
    <Obsolete xsi:nil="true"></Obsolete>
  </Product>
</ArrayOfProduct>

我希望能够像这样格式化Xml:

• 从没有值的行中删除xsi:nil="true"
• 将像<Obsolete></Obsolete>这样的空标签折叠成简单的形式<Obsolete />