System.Security.Principal.GenericPrincipal.AddIdentityWithRoles C# (CSharp) Method

        void AddIdentityWithRoles(IIdentity identity, string[] roles)
        {
            ClaimsIdentity claimsIdentity = identity as ClaimsIdentity;

            if (claimsIdentity != null)
            {
                claimsIdentity = claimsIdentity.Clone();
            }
            else
            {
                claimsIdentity = new ClaimsIdentity(identity);
            }

            // Add 'roles' as external claims so they are not serialized
            // TODO - brentsch, we should be able to replace GenericPrincipal and GenericIdentity with ClaimsPrincipal and ClaimsIdentity
            // hence I am not too concerned about perf.
            List<Claim> roleClaims = new List<Claim>();
            if (roles != null && roles.Length > 0)
            {
                foreach (string role in roles)
                {
                    if (!string.IsNullOrWhiteSpace(role))
                    {
                        roleClaims.Add(new Claim(claimsIdentity.RoleClaimType, role, ClaimValueTypes.String, ClaimsIdentity.DefaultIssuer, ClaimsIdentity.DefaultIssuer, claimsIdentity));
                    }
                }

                claimsIdentity.ExternalClaims.Add(roleClaims);
            }

            base.AddIdentity(claimsIdentity);
        }