Implementing the builder pattern

The Builder pattern is a creational pattern whose goal is to simplify object construction. Instead of having complex constructors that take a large number of parameters, this pattern provides ways to create objects with different states of representation. It gives flexibility while instantiating a class. It provides builder functions to construct the object step by step, and the object will be returned in the final step.

Consider a class that represents a person. We will have to create person objects with different combinations of characteristics. Say, for example, person with firstName, lastName, age, contactNumber, loginId, and address. The class looks as follows:

class Person {
    var firstName: String? = null
    var lastName: String? = null
    var middleName: String? = null
    var loginId: String? = null
    var age: Int? = null
    var contactNumber...