@Override public String lookup(final LogEvent event, final String key) { final boolean isMapMessage = event != null && event.getMessage() instanceof StringMapMessage; if (map == null && !isMapMessage) { return null; } if (map != null && map.containsKey(key)) { final String obj = map.get(key); if (obj != null) { return obj; } } if (isMapMessage) { return ((StringMapMessage) event.getMessage()).get(key); } return null; }