ExpirationDate on Folder not being set

[EthernetIp]

Folder newFolder = new Folder(); newFolder.Name = "somename"; //newFolder.ExpirationDate = DateTime.UtcNow.AddDays(10); newFolder=sfClient.Items.CreateFolder(parentUri, newFolder).Execute();

The above set nothing

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Try 2 Folder newFolder = new Folder(); newFolder.Name = newFolderName; newFolder=sfClient.Items.CreateFolder(parentUri, newFolder).Execute();

newFolder.ExpirationDate = DateTime.UtcNow.AddDays(19); sfClient.Items.Update(newFolder.url, newFolder).Execute();

Works, but why cant this be done at creation ?