bundles/org.eclipse.e4.ui.workbench.fragment/fragment.xml

<?xml version="1.0" encoding="UTF-8"?>
<?eclipse version="3.2"?>
<fragment>
   <extension
         point="org.eclipse.e4.workbench.partfactory">
      <factory
            class="org.eclipse.e4.extensions.LegacyViewFactory">
      </factory>
   </extension>

</fragment>