Index: Src/GoogleApis.Auth/OAuth2/Requests/GoogleAssertionTokenRequest.cs
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+/*
+Copyright 2013 Google Inc
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+
+namespace Google.Apis.Auth.OAuth2.Requests
+{
+    /// <summary>
+    /// Service account assertion token request as specified in 
+    /// https://developers.google.com/accounts/docs/OAuth2ServiceAccount#makingrequest.
+    /// </summary>
+    public class GoogleAssertionTokenRequest : TokenRequest
+    {
+        /// <summary>Gets or sets the JWT (including signature).</summary>
+        [Google.Apis.Util.RequestParameterAttribute("assertion")]
+        public string Assertion { get; set; }
+
+        /// <summary>
+        /// Constructs a new refresh code token request and sets grant_type to 
+        /// <c>urn:ietf:params:oauth:grant-type:jwt-bearer</c>.
+        /// </summary>
+        public GoogleAssertionTokenRequest()
+        {
+            GrantType = @"urn:ietf:params:oauth:grant-type:jwt-bearer";
+        }
+    }
+}