title: Changing the trailing icon color in ExpansionTile
body: <p>I need to change the color of the trailing <code>keyboard_down_arrow</code> in <code>ExpansionTile</code>. I have tried wrapping it in Theme widget and setting accent, primary and IconTheme also, but nothing seems to work.</p>
  <pre><code>Theme(
                    data: Theme.of(context).copyWith(
                      dividerColor: Colors.transparent,
                      accentColor: Colors.black,
                    ),
                    child: ExpansionTile(
                      //
                      title: Text(&quot;Some Text&quot;
                      ),
                      childrenPadding: EdgeInsets.symmetric(horizontal: 15),
                      children: [
                        
                      ],
                    ),
                  ),
  </code></pre>