title: Angular2. How to observer sub-object changes?
body: <p>Suppose I have component with </p>
  
  <pre><code>@Input() timeData: TimeData
  </code></pre>
  
  <p>where <code>TimeData</code> contains only one field: <code>time</code>.</p>
  
  <p>I want to observe <code>timeData.time</code>, <strong>assuming that only <code>timeData.time</code> was changed (not the whole <code>timeData</code>)</strong></p>
  
  <p><code>ngOnChanges</code> doesn't track such change, while <code>{{timeData.time}}</code> works perfect.</p>
  
  <p>My final goal is to set flag <code>goodTime</code></p>
  
  <pre><code>if(timeData.time % 10 === 0){
      goodTime = true
  }
  </code></pre>