title: Unable to put null values in JSON object
body: <p>I am trying to pass parameter to api using JSON.</p>
  
  <pre><code>class Sample
  { ...
     String token;
  ...
  
  void method()
  { ...
      JSONObject params = new JSONObject();
      params.put(KEY_TOKEN,token);
      params.put(KEY_DATE,date);
  
      Log.e("params ",params+"");
  
  
        ...  }    
  </code></pre>
  
  <p>I get the value of params as <code>{"date":"2017-06-19"}</code> but token is seen nowhere.
  I have not initialized token and its value is null as its an instance variable. So is it something that uninitialized value are not included?</p>