This is the business requirement:

" A Holiday Package (e.g. New York NY Holiday Package) can be offered in different ways based on the Origin city:

• From New Delhi to NY
• From Bombay to NY
• NY itself ( Land package )

(Bold implies default selection)

a. and b. User can fly from either New Delhi or Bombay to NY.
c. NY is a Land package, where a user can reach NY by himself and is a standalone holidayPackage. "

Let's say I have a class that represents HolidayPackage, Destination (aka City).

public class HolidayPackage{
    Destination holidayCity;
    ArrayList<BaseHolidayPackageVariant> variants;
    BaseHolidayPackageVariant defaultVariant;
}

public abstract class BaseHolidayPackageVariant {
    private Integer variantId;
    private HolidayPackage holidayPackage;
    private String holidayPackageType;
}

public class LandHolidayPackageVariant extends BaseHolidayPackageVariant{
}

public class FlightHolidayPackageVariant extends BaseHolidayPackageVariant{
    private Destination originCity;
}

What data structure/objects should I design to support:

• options
• a default within those options

Sidenote: A HolidayPackage can also be offered in different ways based on Hotel selections. I'd like to follow a design which I can leverage to support that use case in the future.

This is the backend design I have in mind.