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

        public virtual System.Collections.Generic.IEnumerable<System.Security.Claims.Claim> FindAll(string type) { throw null; }
        public virtual System.Security.Claims.Claim FindFirst(System.Predicate<System.Security.Claims.Claim> match) { throw null; }

        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();
        }