If we're building with JDK8, then clearly we're sticking to
                   JDK8 APIs. However, I assume (but did not confirm) that we'd
                   have the same issue with our -android builds, which need
                   animal-sniffer so that they can check that we're sticking to
                   JDK6-like APIs.

                   So instead, we use javac9, which doesn't lead to this error.
              -->

          <show>package</show>
        </configuration>
      </plugin>
      <!-- Disable "normal" testing, which doesn't work for GWT tests. -->
      <plugin>