public AdUser(LdapEntry entry)
{
Firstname = entry.TryGetAttribute("givenName")?.StringValue ?? "";
Lastname = entry.TryGetAttribute("sn")?.StringValue ?? "";
Email = entry.TryGetAttribute("mail")?.StringValue ?? "";
Cn = entry.TryGetAttribute("cn")?.StringValue ?? "";
Dn = entry.Dn;
PupilId = entry.TryGetAttribute("employeeid")?.StringValue;
TeacherId = entry.TryGetAttribute("description")?.StringValue;
GroupMemberhips = entry.TryGetAttribute("memberof")?.StringValueArray ?? Array.Empty <string>();
}