System.Security.Claims.ClaimsIdentity.FindAll C# (CSharp) Method

        public virtual IEnumerable<Claim> FindAll(string type)
        {
            if (type == null)
            {
                throw new ArgumentNullException(nameof(type));
            }

            Contract.EndContractBlock();

            foreach (Claim claim in Claims)
            {
                if (claim != null)
                {
                    if (string.Equals(claim.Type, type, StringComparison.OrdinalIgnoreCase))
                    {
                        yield return claim;
                    }
                }
            }
        }

        public static async Task<List<string>> GetGroups(ClaimsIdentity claimsId)
        {
            if (claimsId.FindFirst("_claim_names") != null
                && (Json.Decode(claimsId.FindFirst("_claim_names").Value)).groups != null)
                return await GetGroupsFromGraphAPI(claimsId);

            return claimsId.FindAll("groups").Select(c => c.Value).ToList();
        }