Не могу понять,что делает метод(

public interface Application {
 
    static ApplicationMenu start() throws InvalidStateException {
        
        final Supplier<ApplicationContext> applicationContextSupplier = null; // todo
        final NassaContext nassaContext = new NassaContext();
 
        nassaContext.init();
        return applicationContextSupplier::get;
    }
}
 
public interface ApplicationContext {
    <T extends BaseEntity>Collection<T> retrieveBaseEntityList(Class<T> tClass);
    void init() throws InvalidStateException;
}
 
 
@FunctionalInterface
public interface ApplicationMenu {
 
    ApplicationContext getApplicationContext();
 
    default Object printAvailableOptions() {
        return null;
    }
 
    default Object handleUserInput(Object o) {
        return null;
    }
}
 
 
public class NassaContext implements ApplicationContext {
 
    // no getters/setters for them
    private Collection<CrewMember> crewMembers = new ArrayList<>();
    private Collection<Spaceship> spaceships = new ArrayList<>();
    private Collection<Planet> planetMap = new ArrayList<>();
 
    @Override
    public <T extends BaseEntity> Collection<T> retrieveBaseEntityList(Class<T> tClass) {
        return null;
    }
 
    /**
     * You have to read input files, populate collections
     * @throws InvalidStateException
     */
    @Override
    public void init() throws InvalidStateException {
        
    }