title: Setting custom header using HttpURLConnection
body: <p>I am simply making a <code>GET</code> request to a Rest API using <code>HttpURLConnection</code>.</p>
  
  <p>I need to add some custom headers but I am getting <code>null</code> while trying to retrieve their values.</p>
  
  <p><strong>Code:</strong></p>
  
  <pre><code>URL url;
  try {
      url = new URL("http://www.example.com/rest/");
      HttpURLConnection conn = (HttpURLConnection) url.openConnection();
  
      // Set Headers
      conn.setRequestProperty("CustomHeader", "someValue");
      conn.setRequestProperty("accept", "application/json");
  
      // Output is null here &lt;--------
      System.out.println(conn.getHeaderField("CustomHeader"));
  
      // Request not successful
      if (conn.getResponseCode() != HttpURLConnection.HTTP_OK) {
          throw new RuntimeException("Request Failed. HTTP Error Code: " + conn.getResponseCode());
      }
  
      // Read response
      BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
      StringBuffer jsonString = new StringBuffer();
      String line;
      while ((line = br.readLine()) != null) {
          jsonString.append(line);
      }
      br.close();
      conn.disconnect();
  } catch (IOException e) {
      e.printStackTrace();
  }
  </code></pre>
  
  <p>What am I missing?</p>