title: MutableliveData returns null from repository to singleLiveEvent
body: <p>I am trying to call the network on button click. I am using singleLiveEvent wrapper because the data need to be sent to the server and retrieve the response only on button click. I am using Volley for GET and POST calls. I am getting response on repository but not on onChanged method. Its getting null from repository.</p>
  
  <p>Viewmodel class</p>
  
  <pre><code> public void setResponseSingleLiveEvent(String url,Map param){
  
      responseSingleLiveEvent.setValue(mRepository.changeUserPassword(url,param).getValue());
  
  }
  </code></pre>
  
  <p>Repository class</p>
  
  <pre><code>  public MutableLiveData&lt;CommonServerResponse&gt; changeUserPassword(String url, Map params) {
  
      this.postParams = params;
  
      final MutableLiveData&lt;CommonServerResponse&gt; responseMutableLiveData = new MutableLiveData&lt;&gt;();
  
      VolleycustomRequest&lt;CommonModel&gt; volleycustomRequest = new VolleycustomRequest&lt;CommonModel&gt;(Request.Method.POST,
              url, CommonModel.class,
              (Response.Listener&lt;CommonModel&gt;)
                      response -&gt; {
                          Log.d(TAG, "changeUserPassword: "+response);
  
          responseMutableLiveData.setValue(new CommonServerResponse(response));
                      },
              error -&gt; {
          responseMutableLiveData.setValue(new CommonServerResponse(VolleyErrorHelper.getMessage(error)));
              }){
  
          @Override
          protected Map&lt;String, String&gt; getParams() throws AuthFailureError {
              return params;
          }
      };
  
      AppController.getInstance().addToRequestque(volleycustomRequest);
      return responseMutableLiveData;
  }
  </code></pre>
  
  <p>I want the data to be sent only on button click, not on the start of activity.</p>