assertThat(fileAppenderFactory.build(new LoggerContext(), "test", new DropwizardLayoutFactory(), new NullLevelFilterFactory<>(), new AsyncLoggingEventAppenderFactory()))
            .isInstanceOfSatisfying(AsyncAppender.class, asyncAppender -> assertThat(asyncAppender)
                .extracting(appender -> appender.getAppender("file-appender"))
                .satisfies(fileAppender -> assertThat(isImmediateFlushField.get(fileAppender)).isEqualTo(fileAppenderFactory.isImmediateFlush())));