HW 5: Implement this and its Multicast version - observers interface ...update( o: Observable, addObserver(o: Observer): void setChanged): void hasChanged():boolean clearChanged(): void (arg: Object): void TableObserver update(...: void update!. ): void update..): void StockEvent a map of ticker and quote ticker: String uote: float t: String, float): void Update a map with t and q setChanged0 notifyObservers(new QuoteEvent(t, q)); StockEvent) arg, arg.getTicker and arg.getQuote() 19