title: contentDetails or duration not coming using Youtube v3 api
body: <p>Look at this <a href="https://developers.google.com/youtube/v3/getting-started" rel="noreferrer">link</a> , there is an example given</p>
  
  <pre><code>https://www.googleapis.com/youtube/v3/videos?id=7lCDEYXw3mM&amp;key=YOUR_API_KEY
   &amp;part=snippet,contentDetails,statistics,status
  </code></pre>
  
  <p>Part of the response is</p>
  
  <pre><code>"contentDetails": {
      "duration": "PT15M51S",
      "aspectRatio": "RATIO_16_9"
     },
  </code></pre>
  
  <p>Now I want to retrieve contentDetails or mainly duration. So I called using</p>
  
  <pre><code>https://www.googleapis.com/youtube/v3/search?part=snippet,contentDetails&amp;key=[API_KEY]&amp;q=something&amp;maxResults=15&amp;&amp;fields=items,nextPageToken,prevPageToken,tokenPagination
  </code></pre>
  
  <p>It shows</p>
  
  <pre><code>{
  error: {
  errors: [
  {
  domain: "youtube.part",
  reason: "unknownPart",
  message: "contentDetails",
  locationType: "parameter",
  location: "part"
  }
  ],
  code: 400,
  message: "contentDetails"
  }
  }
  </code></pre>
  
  <p>Why? What am I missing? How to retrieve the duration for videos?</p>