fix(ConfigurableMessageHandler): Fix quota project header on retry

Author: robertvoinescu-work

Src/Support/Google.Apis.Auth/OAuth2/AccessTokenWithHeaders.cs

@@ -17,6 +17,7 @@ limitations under the License.
 using Google.Apis.Util;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
+using System.Linq;
 using System.Net.Http;
 using System.Net.Http.Headers;
 
@@ -78,6 +79,8 @@ public void AddHeaders(HttpRequestHeaders requestHeaders)
 
             foreach (var header in Headers)
             {
+                // Overwite any pre-existing header with the provided values.
+                requestHeaders.Remove(header.Key);
                 requestHeaders.Add(header.Key, header.Value);
             }
         }

Src/Support/Google.Apis.Core/Http/ConfigurableMessageHandler.cs

@@ -641,6 +641,10 @@ bool DisposeAndReturnFalse(IDisposable disposable)
                         }
                     }
                 }
+
+                // Reset the quota project here so we can validate a new project isn't specified by the interceptors.
+                // In any case this will be repopulated by the credential interceptor.
+                request.Headers.Remove(QuotaProjectHeaderName);
             } while (triesRemaining > 0); // Not a successful status code but it was handled.
 
             // If the response is null, we should throw the last exception.