this.clss = clss;
this.clss = listener;
    public Notifier(Class listener) {        if(listener == null) {            throw new IllegalArgumentException("Illegal to have a null listener Class. ");        }                this.clss = clss;        // now we check methods, if only one of them, then         // let's set it        Method[] meths = clss.getDeclaredMethods();        if(meths.length == 0) {            this.listenerMethod = meths[0];        }    }