HttpClientExtensions.cs

    internal static class HttpClientExtensions
    {
        public static Task<HttpResponseMessage> PostAsJsonAsync<T>(this HttpClient client, string uri, T content, string messageId = null)
            => SendAsJsonAsync<T>(client, HttpMethod.Post, uri, content, messageId);         

        public static Task<HttpResponseMessage> PutAsJsonAsync<T>(this HttpClient client, string uri, T content)
            => SendAsJsonAsync<T>(client, HttpMethod.Put, uri, content, null);

        public static Task<HttpResponseMessage> GetAsync(this HttpClient client, string uri)
        {
            var request = BuildRequest(HttpMethod.Get, uri);

            return client.SendAsync(request);
        }

        private static async Task<HttpResponseMessage> SendAsJsonAsync<T>(HttpClient client, HttpMethod method, string uri, T content, string messageId = null)
        {
            var request = BuildRequest(method, uri, messageId: messageId);
            request.Content = new StringContent(JsonConvert.SerializeObject(content), Encoding.UTF8, "application/json");

            var response = await client.SendAsync(request);

            return response;
        }

        private static HttpRequestMessage BuildRequest(HttpMethod method, string uri, string messageId = null)
        {
            var request = new HttpRequestMessage(method, uri);

            if (request.Headers.Contains("Accept") == false)
            {
                request.Headers.Add("Accept", "application/json");
            }

            return request;
        }
    }