public interface IPluginMetadata{    string Name { get; }    [DefaultValue(1)]      int Version { get; }}[Export(typeof(IPlugin)),    ExportMetadata("Name", "Logger"),    ExportMetadata("Version", 4)]public class Logger : IPlugin{}[Export(typeof(IPlugin)),    ExportMetadata("Name", "Disk Writer")]     //Version is not required because of the DefaultValuepublic class DWriter : IPlugin{}//----public class Addin{    [Import]    public Lazy
     
       plugin;}//-------public class User{    [ImportMany]    public IEnumerable
      
       
        > plugins;    public IPlugin InstantiateLogger ()    {        IPlugin logger = null;        foreach (Lazy
        
          plugin in plugins)        {            if (plugin.Metadata.Name = "Logger") logger = plugin.Value;        }        return logger;    }}//------