ADFS custom attribute store with multiple values

CAS.cs

using Microsoft.IdentityServer.ClaimsPolicy.Engine.AttributeStore;
using System;
using System.Collections.Generic;
using System.IdentityModel;

namespace CAStore
{
    public class CAS : IAttributeStore
    {
        public IAsyncResult BeginExecuteQuery(string query, string[] parameters, AsyncCallback callback, object state)
        {
            // c:[Type == "http://schemas.xmlsoap.org/ws/2005/05/identity/claims/upn"]
            // => issue(store = "CAS", types = ("http://schemas.myorganization.com/identity/uppercaseupn"), query = "toUpper", param = c.Value);

            // query = "toUpper"
            // parameters [0] = UPN = [email protected]
            
            if (String.IsNullOrEmpty(query))
            {
                throw new AttributeStoreQueryFormatException("No query string.");
            }

            if (parameters == null)
            {
                throw new AttributeStoreQueryFormatException("No query parameter.");
            }

            if (parameters.Length != 1)
            {
                throw new AttributeStoreQueryFormatException("More than one query parameter.");
            }

            string inputString = parameters[0];

            if (inputString == null)
            {
                throw new AttributeStoreQueryFormatException("Query parameter cannot be null.");
            }

            if (!query.Equals("House"))
                throw new AttributeStoreQueryFormatException("The query string " + query + " is not supported.");

            // string[][] outputValues
            // C# jagged array. 
            // There is only one query viz. "HouseID". So each row can only have 1 column. If there were 3 queries e.g. "GivenName, sn, HouseID", then each row would have 3 columns.
            // The search has multiple results so we have many rows; each with one column.

            try
            {
                // Dummy value to illustrate the principle.

                List<string> claimValues = new List<string>();
                claimValues.Add("123456");
                claimValues.Add("654321");
                claimValues.Add("456123");
                
                List<string[]> claimData = new List<string[]>();

                // Each claim value is added to its own string array 
                foreach (string claimVal in claimValues)
                {
                    claimData.Add(new string[1] { claimVal });
                }

                // The claim value string arrays are added to the string [][] that is returned by the Custom Attribute Store EndExecuteQuery()
                string[][] resultData = claimData.ToArray();

                TypedAsyncResult<string[][]> asyncResult = new TypedAsyncResult<string[][]>(callback, state);
                asyncResult.Complete(resultData, true);
                return asyncResult;
            }

            catch (Exception ex)
            {
                String innerMess = "";
                if (ex.InnerException != null)
                    innerMess = ex.InnerException.ToString();

                throw new AttributeStoreQueryExecutionException("CAS exception : " + ex.Message + " " + innerMess);
            }
        }

        public string[][] EndExecuteQuery(IAsyncResult result)
        {
            return TypedAsyncResult<string[][]>.End(result);
        }

        public void Initialize(Dictionary<string, string> config)
        {
            // No initialization is required for this store.  
        }
    }
}

http://nzpcmad.blogspot.co.nz/2017/03/adfs-creating-custom-attribute-store.html