Sharpkml在文件夹中插入图标

        <?xml version="1.0" encoding="utf-8"?>
        <kml xmlns:gx="http://www.google.com/kml/ext/2.2" xmlns="http://www.opengis.net/kml/2.2">
         <Document>
          <name>Doc</name>
          <Folder>
            <name>fol1</name>
              <Icon>
                <href>green.png</href>
               </Icon>
           </Folder>
        </Document>
        </kml>

Kml kml = new Kml(); 
kml.AddNamespacePrefix(KmlNamespaces.GX22Prefix, KmlNamespaces.GX22Namespace); 
var document = new Document(); 
document.Name = "Doc"; 
kml.Feature = document; 
var folder1 = new Folder(); 
folder1.Name = "fol1"; 
document.AddFeature(folder1);