tests/org.eclipse.core.tests.runtime/Plugin_Testing/extensiveRequiresTest/optional2RequiresTest.xml

<?xml version="1.0" encoding="UTF-8"?>
<plugin
  name="Optional 2 Requires Test"
  id="optional2RequiresTest"
  version="1.2"
  vendor-name="OTI">

  <requires>
     <import plugin="tests.b" optional="true"/>
  </requires>

</plugin>