...

var libItemService = ServiceManager.VapiConnection.GetService<Item>();
var itemFilesService = ServiceManager.VapiConnection.GetService<
vmware.content.library.item.File>();

// List the items in a published library
foreach (var itemId in libItemService.List(libraryId))
{

     // List the files uploaded to each library item and print their names and size
     foreach (var singleFile in itemFilesService.List(itemId))
     {
         Console.WriteLine("Library item with name " + singleFile.GetName() +
             " has size " + singleFile.GetSize());
     }

     // Change the name and description of the library item with the specified name
     var singleItem = libItemService.Get(itemId);
     if (singleItem.GetName().Equals("simpleVmTemplate"))
     {
          var libItemUpdated = new ItemModel();
          libItemUpdated.SetName("newItemName");
          libItemUpdated.SetDescription("Description of the newItemName");
          libItemService.Update(singleItem.GetId(), libItemUpdated);
      }
}