Check if the header exists and replace it rather than add it again (#299)

Author: flownzu

SpotifyAPI.Web/SpotifyWebClient.cs

@@ -39,10 +39,7 @@ public Tuple<ResponseInfo, byte[]> DownloadRaw(string url, Dictionary<string, st
         {
             if (headers != null)
             {
-                foreach (KeyValuePair<string, string> headerPair in headers)
-                {
-                    _client.DefaultRequestHeaders.TryAddWithoutValidation(headerPair.Key, headerPair.Value);
-                }
+                AddHeaders(headers);
             }
             using (HttpResponseMessage response = Task.Run(() => _client.GetAsync(url)).Result)
             {
@@ -58,10 +55,7 @@ public async Task<Tuple<ResponseInfo, byte[]>> DownloadRawAsync(string url, Dict
         {
             if (headers != null)
             {
-                foreach (KeyValuePair<string, string> headerPair in headers)
-                {
-                    _client.DefaultRequestHeaders.TryAddWithoutValidation(headerPair.Key, headerPair.Value);
-                }
+                AddHeaders(headers);
             }
             using (HttpResponseMessage response = await _client.GetAsync(url).ConfigureAwait(false))
             {
@@ -101,10 +95,7 @@ public Tuple<ResponseInfo, byte[]> UploadRaw(string url, string body, string met
         {
             if (headers != null)
             {
-                foreach (KeyValuePair<string, string> headerPair in headers)
-                {
-                    _client.DefaultRequestHeaders.TryAddWithoutValidation(headerPair.Key, headerPair.Value);
-                }
+                AddHeaders(headers);
             }
 
             HttpRequestMessage message = new HttpRequestMessage(new HttpMethod(method), url)
@@ -125,10 +116,7 @@ public async Task<Tuple<ResponseInfo, byte[]>> UploadRawAsync(string url, string
         {
             if (headers != null)
             {
-                foreach (KeyValuePair<string, string> headerPair in headers)
-                {
-                    _client.DefaultRequestHeaders.TryAddWithoutValidation(headerPair.Key, headerPair.Value);
-                }
+                AddHeaders(headers);
             }
 
             HttpRequestMessage message = new HttpRequestMessage(new HttpMethod(method), url)
@@ -176,6 +164,18 @@ private static WebHeaderCollection ConvertHeaders(HttpResponseHeaders headers)
             return newHeaders;
         }
 
+        private void AddHeaders(Dictionary<string,string> headers)
+        {
+            foreach (KeyValuePair<string, string> headerPair in headers)
+            {
+                if (_client.DefaultRequestHeaders.Contains(headerPair.Key))
+                {
+                    _client.DefaultRequestHeaders.Remove(headerPair.Key);
+                }
+                _client.DefaultRequestHeaders.TryAddWithoutValidation(headerPair.Key, headerPair.Value);
+            }
+        }
+
         private static HttpClientHandler CreateClientHandler(ProxyConfig proxyConfig = null)
         {
             HttpClientHandler clientHandler = new HttpClientHandler