EE Player Class

class Player {
    public int Id { get; }
    public string Username { get; }
    public Player (Message e) {
        if (e == null) throw new ArgumentNullException ();
        switch (e.Type) {
            case "init":
                Id = (int) e[5];
                Username = (string) e[13];
                break;
            case "add":
                Id = (int) e[0];
                Username = (string) e[1];
                break;
            default:
                throw new ArgumentException ("Invalid message type.");
        }
    }
    public Player (int id, string username) {
        if (string.IsNullOrEmpty (username)) throw new ArgumentNullException ();
        Id = id;
        Username = username;
    }
    public static Player FromId (IEnumerable<Player> players, int id) {
        if (players == null) throw new ArgumentNullException ();
        foreach (Player player in players) if (player.Id == id) return player;
        throw new ArgumentException ("No player contains the specified ID.");
    }
    public static Player FromUsername (IEnumerable<Player> players, string username) {
        if (players == null) throw new ArgumentNullException ();
        foreach (Player player in players) if (player.Username == username) return player;
        throw new ArgumentException ("No player contains the specified username.");
    }
}