CommitAsync method returns error 415

[paulofoxbr]

CommitAsync return error 415. Solution is set a ContentType Media.

The rewritten method below:

    public async Task CommitAsync(IEnumerable<string> handles, CancellationToken cancellationToken)
    {
        var path = "api/orders/feed";
        var contentString = JsonSerializer.Serialize(new { handles });

         var request = new HttpRequestMessage(HttpMethod.Post, path)
        {
            Content = new StringContent(contentString)
            { 
                Headers = 
                {
                    ContentType =  new MediaTypeHeaderValue("application/json") // new
                }
            }
        };

        request.Headers.Add("Accept", "application/json"); // new
        request.Headers.Add("X-VTEX-API-AppKey", _appKey);
        request.Headers.Add("X-VTEX-API-AppToken", _appToken);

        

        var response = await _httpClient.SendAsync(request, cancellationToken).ConfigureAwait(false);
        if (!response.IsSuccessStatusCode) throw new Exception($"Unable to execute POST in the path `{path}`, the status code was `{response.StatusCode}`");
    }