Below we have class diagrams with three classes for a simple java based parking management class. Use the classes below to write java code for classes :a parking observer class (that implements an...

Below we have class diagrams with three classes for a simple java based parking management class. Use the classes below to write java code for classes :a parking observer class (that implements an observer pattern)  , a transaction manager class and a parking lot class(subject to the observer). Use the class diagram and java class to implement it. You should use an observer pattern to implement your code.The main goal is to implement the following - Once a car enters (in an entry-scan only lot) or leaves (in an entry-scan and exit-scan lot), then the ParkingObserver will be updated, and then can register the charge with the parking system via the TransactionManager’s park() method