public void RemoveRolle(RolleDTO rolle)
 {
     for (int i = Rollen.Count - 1; i >= 0; i--)
     {
         if (Rollen[i].Name.Equals(rolle.Name, StringComparison.InvariantCultureIgnoreCase))
         {
             Rollen.RemoveAt(i);
         }
     }
 }
 public void AddRolle(RolleDTO rolle)
 {
     RemoveRolle(rolle.Name);
     Rollen.Add(rolle);
 }