title: Can't convert string to system.Net.HttpContent
body: <p>Here I'm trying to get data from the services:</p>
  
  <pre><code>public async Task&lt;IHttpActionResult&gt; ValidateSesion()
  {
      var values = new Dictionary&lt;string, string&gt;{
          { "productId", "1" },
          { "productKey", "Abc6666" },
          { "userName", "OPPO" },
      };
      var json = JsonConvert.SerializeObject(values, Formatting.Indented);
      // var content = new FormUrlEncodedContent(json);
      client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
      var response = await client.PostAsync("http://172.116.12.172:8014/iadmin/validate", json);
      var responseString = await response.Content.ReadAsStringAsync();
      return Ok(responseString);
  }
  </code></pre>
  
  <p>If I make any PostMan call, like below, the data i get looks like this:</p>
  
  <pre><code>{
      "productId": "1",
      "productKey": "Abc6666" 
  }
  </code></pre>