Why does the UserDto<T> Name property have a regex restriction?

[James-Jackson-South]

See the following regex.

IdentityServer4.Admin/src/Skoruba.IdentityServer4.Admin.BusinessLogic.Identity/Dtos/Identity/UserDto.cs

Lines 10 to 12 in 7f810bd

	[Required]
	[RegularExpression(@"^[a-zA-Z0-9_@\-\.\+]+$")]
	public string UserName { get; set; }

This restricts user names sent via the API when creating users which differs from the configurable one for the UI.