Complete the implementations of various classes in a Flight Management System. Read the API for FlightManagementSystem carefully, the API of this lab is available under doc folder in the Java project folder (docindex.html). Some example tests are given to you in the Tester class. You are required to write (at least three) additional tests to further ensure the correctness of your Flight Management implementations. We consider a database that stores information about passengers and flights. Each passenger record (e.g., String name, double TicketAmount, int flightID) can be uniquely identified by a String ID (e.g., e1), whereas each flight record (e.g., String airline and String flight 2 for flight name and airline name, respectively ) can be uniquely identified by an integer id (e.g., 2000). You must implement all methods in the FlightManagementSystem by manipulating the two attributes passengers and flights, each of which declared as a HashMap. class FlightManagementSystem { HashMap flights; HashMap passengers; /* All methods must be implemented via flights and passengers */ } Override the compareTo and equal methods in the PassengerInfo class. Override the equals method in the FlightInfo class.For simplicity, you can assume that a passenger cannot be added in multiple flights. For this question, you are required to submit Java files such as FlightInfo, PassengerInfo, FlightManagementSystem, Tester in your Eclip