ThreadContext.remove("key1");
ThreadContext.remove("key2");
root.error("finished mdc pattern test", new NullPointerException("test"));
appender.stop();
List<String> list = appender.getMessages();
assertTrue("Incorrect number of lines. Require at least 50 " + list.size(), list.size() > 50);
assertTrue("Incorrect header", list.get(0).equals("<?xml version=\"1.0\" encoding=\"UTF-8\"?>"));