Org.BouncyCastle.Pkix.PkixNameConstraintValidator.UnionEmail C# (CSharp) Method

        private ISet UnionEmail(ISet excluded, String email)
        {
            if (excluded.IsEmpty)
            {
                if (email == null)
                {
                    return excluded;
                }
                excluded.Add(email);
                return excluded;
            }
            else
            {
                ISet union = new HashSet();

                IEnumerator it = excluded.GetEnumerator();
                while (it.MoveNext())
                {
                    String _excluded = (String)it.Current;

                    unionEmail(_excluded, email, union);
                }

                return union;
            }
        }