add accept header to all clients

Author: leastprivilege

source/IdentityModel.Shared/Client/IntrospectionClient.cs

@@ -14,10 +14,11 @@
  * limitations under the License.
  */
 
- using System;
+using System;
 using System.Collections.Generic;
 using System.Net;
 using System.Net.Http;
+using System.Net.Http.Headers;
 using System.Threading.Tasks;
 
 namespace IdentityModel.Client
@@ -36,6 +37,10 @@ public IntrospectionClient(string endpoint, string clientId = "", string clientS
                 BaseAddress = new Uri(endpoint)
             };
 
+            _client.DefaultRequestHeaders.Accept.Clear();
+            _client.DefaultRequestHeaders.Accept.Add(
+                new MediaTypeWithQualityHeaderValue("application/json"));
+
             if (!string.IsNullOrWhiteSpace(clientId))
             {
                 _client.SetBasicAuthentication(clientId, clientSecret);

source/IdentityModel.Shared/Client/TokenClient.cs

@@ -18,6 +18,7 @@
 using System.Collections.Generic;
 using System.Net;
 using System.Net.Http;
+using System.Net.Http.Headers;
 using System.Threading;
 using System.Threading.Tasks;
 
@@ -45,6 +46,10 @@ public TokenClient(string address, HttpMessageHandler innerHttpMessageHandler)
                 BaseAddress = new Uri(address)
             };
 
+            _client.DefaultRequestHeaders.Accept.Clear();
+            _client.DefaultRequestHeaders.Accept.Add(
+                new MediaTypeWithQualityHeaderValue("application/json"));
+
             AuthenticationStyle = AuthenticationStyle.None;
         }
 

source/IdentityModel.Shared/Client/UserInfoClient.cs

@@ -17,6 +17,7 @@
 using System;
 using System.Net;
 using System.Net.Http;
+using System.Net.Http.Headers;
 using System.Threading.Tasks;
 
 namespace IdentityModel.Client
@@ -45,6 +46,10 @@ public UserInfoClient(Uri endpoint, string token, HttpMessageHandler innerHttpMe
                 BaseAddress = endpoint
             };
 
+            _client.DefaultRequestHeaders.Accept.Clear();
+            _client.DefaultRequestHeaders.Accept.Add(
+                new MediaTypeWithQualityHeaderValue("application/json"));
+
             _client.SetBearerToken(token);
         }