the add-opens. Right now that doesn't seem worth the effort, though.
        -->
        <test.add.opens>
          --add-opens java.base/java.lang=ALL-UNNAMED
          --add-opens java.base/java.util=ALL-UNNAMED
          --add-opens java.base/sun.security.jca=ALL-UNNAMED
        </test.add.opens>
      </properties>
    </profile>
    <profile>

            like to get an error. Currently we do, but if we add the extra <inherits> lines, we
            won't.

            I have one idea for a better approach, but it's painful, and I haven't tested it: We
            could postprocess Collect.gwt.xml to add <skip> lines for all the files that should be
            covered by testModule.gwt.xml. Maybe I'll try it someday.