@SuppressWarnings("unused") // https://errorprone.info/bugpattern/FutureReturnValueIgnored
    Future<?> possiblyIgnoredError = testExecutor.schedule(DO_NOTHING, 10, MINUTES);
    mock.assertLastMethodCalled("scheduleRunnable", 10, MINUTES);

    @SuppressWarnings("unused") // https://errorprone.info/bugpattern/FutureReturnValueIgnored
    Future<?> possiblyIgnoredError1 =
        testExecutor.schedule(Executors.callable(DO_NOTHING), 5, SECONDS);