Extension - Create an enumerable from an object

The following is a simple little extension that takes an object, and returns an IEnumerable with that object as it's first and only element. I originally wrote it for a project called Cloud-X, and put it here as I included it in Project Hermes:

/// 
/// Takes an object af any type, and returns a list of that type with the object as it's first item.
/// 
public static IEnumerable ToEnumerable(this T firstItem) =>
  firstItem == null ? new List(0) : new List(1) { firstItem };