Issue 432: Batch request with null callback throws exception

Src/GoogleApis/Apis/Requests/BatchRequest.cs

 /*
 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
@@ skipping 83 matching lines @@
 private class InnerRequest<TResponse> : InnerRequest
 where TResponse : class
 {
 /// <summary>Gets or sets a concrete type callback for an individual
response. </summary>
 public OnResponse<TResponse> OnResponseCallback { get; set; }
 
 public override void OnResponse(object content, RequestError error,
int index,
 HttpResponseMessage message)
 {
 base.OnResponse(content, error, index, message);
+if (OnResponseCallback == null)
+return;
+
 OnResponseCallback(content as TResponse, error, index, message);
 }
 }
 
 #endregion
 
 /// <summary>
 /// Constructs a new batch request using the given service. See·
 /// <see cref="BatchRequest(IClientService, string)"/> for more informat
ion.
 /// </summary>
@@ skipping 37 matching lines @@
 });
 }
 
 /// <summary>Asynchronously executes the batch request.</summary>
 public Task ExecuteAsync()
 {
 return ExecuteAsync(CancellationToken.None);
 }
 
 /// <summary>Asynchronously executes the batch request.</summary>
- /// <param name="taskCancellationToken">Cancellation token to cancel ope
 ration.</param>
+ /// <param name="cancellationToken">Cancellation token to cancel operati
 on.</param>
 public async Task ExecuteAsync(CancellationToken cancellationToken)
 {
 if (Count < 1)
 return;
 
 ConfigurableHttpClient httpClient = service.HttpClient;
 
 var requests = from r in allRequests
 select r.ClientRequest;
 HttpContent outerContent = await CreateOuterRequestContent(requests)
.ConfigureAwait(false);
@@ skipping 182 matching lines @@
 var content = await requestMessage.Content.ReadAsStringAsync().C
onfigureAwait(false);
 sb.Append("Content-Length: ").Append(content.Length);
 
 sb.Append(Environment.NewLine).Append(Environment.NewLine).Appen
d(content);
 }
 
 return sb.Append(Environment.NewLine).ToString();
 }
 }
 }