public void addAppender(Appender<E> newAppender) {
        if (newAppender == null) {
            throw new IllegalArgumentException("Null argument disallowed");
        }
        appenderList.addIfAbsent(newAppender);
    }
@Test
    public void testAddAppender() throws Exception {
        TestEvent event = new TestEvent();
        NOPAppender<TestEvent> ta = new NOPAppender<TestEvent>();
        ta.start();
        aai.addAppender(ta);
        ta = new NOPAppender<TestEvent>();
        ta.setName("test");
        ta.start();
        aai.addAppender(ta);
        int size = aai.appendLoopOnAppenders(event);
        Assertions.assertTrue(size == 2, "Incorrect number of appenders");
    }