plugins/org.eclipse.xtend.middleend.xtend.ui/plugin.xml

<?xml version="1.0" encoding="UTF-8"?>
<?eclipse version="3.4"?>
<plugin>
   <extension
         point="org.eclipse.xtend.backend.ui.MiddleEndConfigurer">
      <element_1
            class="org.eclipse.xtend.middleend.xtend.ui.XtendMiddleEndConfigurer">
      </element_1>
   </extension>

</plugin>