is the location of a file that needs to exist, and if it doesn't, the profile will be
        activated. On the other hand, {@code exists} will test for the existence of the file and if it is
        there, the profile will be activated.
        <p>Variable interpolation for these file specifications is limited to {@code ${project.basedir}},

        <artifactId>maven-compiler-plugin</artifactId>
        <configuration>
          <excludes>
            <!-- Yes, we want to exclude ForceGuavaCompilation 4 times: -->
            <!-- (And we might as well exclude DummyJavadocClass 3 times (though it would be harmless to include).) -->
            <!-- 1. Don't compile it (since that requires a *non-test* dep on gwt-user. -->
            <exclude>**/ForceGuavaCompilation*</exclude>