added support for token type hint

Author: leastprivilege

source/IdentityModel.Shared/Client/IntrospectionClient.cs

@@ -52,9 +52,17 @@ public TimeSpan Timeout
 
         public async Task<IntrospectionResponse> SendAsync(IntrospectionRequest request)
         {
+            if (request == null) throw new ArgumentNullException("request");
+            if (string.IsNullOrWhiteSpace(request.Token)) throw new ArgumentNullException("token");
+
             var form = new Dictionary<string, string>();
             form.Add("token", request.Token);
 
+            if (!string.IsNullOrWhiteSpace(request.TokenTypeHint))
+            {
+                form.Add("token_type_hint", request.TokenTypeHint);
+            }
+
             if (string.IsNullOrWhiteSpace(request.ClientId))
             {
                 form.Add("client_id", request.ClientId);

source/IdentityModel.Shared/Client/IntrospectionRequest.cs

@@ -19,6 +19,7 @@ namespace IdentityModel.Client
     public class IntrospectionRequest
     {
         public string Token { get; set; }
+        public string TokenTypeHint { get; set; }
 
         public string ClientId { get; set; }
         public string ClientSecret { get; set; }