title: How to set form value while using google map with ant design Form.Item?
body: <p>I have created a custom <code>&lt;GoogleMap /&gt;</code> component (wrapper for react-google-map) which returns the latitude, longitude and zoomlevel on onClick event of the GoogleMap component. Now I want to wrap it up with the <code>ant.design</code> <code>Form.Item</code> component with the <code>form.getFieldDecorator</code> but can't find a way to do it?
  All I could do is</p>
  
  <pre><code>&lt;Form.Item label="Point a location"&gt;
     {
       form.getFieldDecorator('map', {
         valuePropName: 'onClick',
         getValueFromEvent: mapData =&gt; {
          console.log('mapData', mapData);
          return mapData;
         }
       })(
         &lt;div&gt;
           &lt;GoogleMap onClick={data =&gt; { console.log('Passed data to parent', data); }} /&gt;
         &lt;/div&gt;
       )}
  &lt;/Form.Item&gt;
  </code></pre>
  
  <p>The on click event does log into the console but doesn't set the value or call the getValueFromEvent function. Any help is appreciated.</p>