contains com.google.common.util.concurrent.ListenableFuture class, without
    any other Guava classes. The idea is:

    - If users want only ListenableFuture, they depend on listenablefuture-1.0.

    - If users want all of Guava, they depend on guava, which, as of Guava
    27.0, depends on
    listenablefuture-9999.0-empty-to-avoid-conflict-with-guava. The 9999.0-...

    "version" that omits the class to avoid conflicts with the copy in Guava
    itself. The idea is:

    - If users want only ListenableFuture, they depend on listenablefuture-1.0.

    - If users want all of Guava, they depend on guava, which, as of Guava
    27.0, depends on
    listenablefuture-9999.0-empty-to-avoid-conflict-with-guava. The 9999.0-...

            <!-- Even after we stop using JSR305 annotations in our own code, we'll want this link so that NullPointerTester's docs can link to @CheckForNull and friends... at least once we start using this config for guava-testlib. -->
            <offlineLink>

              <testTimeOut>86400 <!-- seconds --></testTimeOut>
              <testMethodTimeout>1440 <!-- minutes --></testMethodTimeout>
              <!-- Presumably we want watchFileChanges=false here, since we want it for compile: -->
              <extraJvmArgs>-Dgwt.watchFileChanges=false</extraJvmArgs>
            </configuration>
          </execution>
        </executions>
      </plugin>

            <!-- Even after we stop using JSR305 annotations in our own code, we'll want this link so that NullPointerTester's docs can link to @CheckForNull and friends... at least once we start using this config for guava-testlib. -->
            <offlineLink>