By accessing a simple REST API, we're creating a user model class. When the client inputs a correct username and password, this will return a simple JSON output of some user details.

Here is the code of Users.kt:

class Users(val id: String,
            val name: String,
            val email: String,
            val contactNumber: String)

 In this user model, we have an id, a name, an email, and a contactNumber. We'll create a JSON-type REST API that will be protected by our security system.