/// <summary>
 /// Selects a top level value from the json user data with the given key name and adds it as a Claim.
 /// This no-ops if the ClaimsIdentity already contains a Claim with the given ClaimType.
 /// This no-ops if the key is not found or the value is empty.
 /// </summary>
 /// <param name="collection"></param>
 /// <param name="claimType">The value to use for Claim.Type when creating a Claim.</param>
 /// <param name="jsonKey">The top level key to look for in the json user data.</param>
 public static void P7MapUniqueJsonKey(this ClaimActionCollection collection, string claimType, string jsonKey)
 {
     collection.P7MapUniqueJsonKey(claimType, jsonKey, ClaimValueTypes.String);
 }