#fixed code
                                public void startServer(IConfig config, List<? extends InterceptHandler> handlers) throws IOException {
        startServer(config, handlers, null, null, null);
    }
#vulnerable code 
                                public void startServer(IConfig config, List<? extends InterceptHandler> handlers) throws IOException {
        startServer(config, handlers, null);
    } 
                            #location 2 
                            #vulnerability type NULL_DEREFERENCE