title: how to set materialButton icon to the center
body: <p>I am using <strong>supportLibrary = &quot;28.0.0-beta01&quot;</strong> version.<br />
  Here is my code in .xml file:</p>
  <pre><code>&lt;android.support.design.button.MaterialButton
      android:layout_width=&quot;match_parent&quot;
      android:layout_height=&quot;wrap_content&quot;
      app:icon=&quot;@drawable/ic_my_orders&quot;
      app:iconGravity=&quot;textStart&quot;
      android:gravity=&quot;center&quot;/&gt;
  </code></pre>
  <p>To my code icon of the drawable locating left side of the button. I want to set button to the center.
  <em>I want to achieve this result</em>
  <a href="https://i.stack.imgur.com/68OlS.png" rel="noreferrer"><img src="https://i.stack.imgur.com/68OlS.png" alt="enter image description here" /></a></p>
  <hr />
  <h2>Edit</h2>
  <p>I don't need to any custom views or hard coded things. If this is a bug (app:iconGravity), I will wait next release.</p>
  <h2>EDIT</h2>
  <p>The bug fixed in the version <strong>28.0.0-rc01</strong>,just change the version.</p>