/// <summary>
 /// Adds a reviewer to a an already created pull request.
 /// </summary>
 /// <param name="gitHttpClient">GitHttpClient that is created for accessing vsts</param>
 /// <param name="pullRequest"> pull request that is already created.</param>
 /// <param name="identity">identity of the reviewer that we want to add to the pull request.</param>
 public static async Task AddReviewerToPullRequest(GitHttpClient gitHttpClient, GitPullRequest pullRequest, IdentityRefWithVote identity)
 {
     identity = await gitHttpClient.CreatePullRequestReviewerAsync(
         identity,
         pullRequest.Repository.Id,
         pullRequest.PullRequestId,
         identity.Id).ConfigureAwait(false);
 }