title: Custom Header is not displayed in DOM content when using Enzyme or React Testing Library
body: <p>We are using custom headers in ag-grid community version. We have written unit tests in both Enzyme and React testing Library.</p>
  
  <p>Till ag-grid-community version "21.2.2", we are able to see the below customheader in DOM content.</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div class="ag-react-container"&gt;
      &lt;div&gt;
         &lt;div class="customHeaderLabel"&gt;SanMake&lt;/div&gt;
      &lt;/div&gt;
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>From version "22.1.0", we are unable to see the above DOM content in the unit tests. Could you please help with the solution. As we are having several unit tests written for custom headers, all the unit tests are failing - when we try to upgrade version to "22.1.0".</p>