title: Volley doesn't cache post request
body: <p>I fetch data from server with following method:</p>
  
  <pre><code>public void process(final String url){
          this.url=url;
          GsonRequest&lt;T&gt; request=new GsonRequest&lt;&gt;(url, responseType, requestData, new Response.Listener&lt;T&gt;() {
              @Override
              public void onResponse(T response) {
                  //handle response here
              }
          }, new Response.ErrorListener() {
              @Override
              public void onErrorResponse(VolleyError error) {                                        
                  //handle error here
              }
          });
          request.setRetryPolicy(new DefaultRetryPolicy(
                  0,
                  DefaultRetryPolicy.DEFAULT_MAX_RETRIES,
                  DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));
          request.setShouldCache(true);
          queue.add(request);
   }
  </code></pre>
  
  <p>Some of the requests fetch signficant amount of data.I'd like <code>Volley</code> to cache data in some cases.However when I do one of these heavy request and then turn network off and then repeat my request Volley throws 
  <code>java.net.UnknownHostException: Unable to resolve host "...": No address associated with hostname</code>.
  Is there something I can do to make Volley cache responses?</p>