Response Unmarshaller for AttachVolume operation
Inheritance: EC2ResponseUnmarshaller
 public static AttachVolumeResponseUnmarshaller GetInstance()
 {
     if (instance == null) 
     {
        instance = new AttachVolumeResponseUnmarshaller();
     }
     return instance;
 }
 public static AttachVolumeResponseUnmarshaller GetInstance()
 {
     if (instance == null)
     {
         instance = new AttachVolumeResponseUnmarshaller();
     }
     return(instance);
 }