class Student(val id: Int?,
              val name: String?,
              val age: Age?)

class Age(var day: Int?,
          var month: Int?,
          var year: Int?)


class ProblemChild {
    fun begin() {
        val age = Age(1, 11, 2012)
        val student = Student(21, "Nick", age)
        System.out.println(student.age)
        age.month = age.year
        age.day = 12
        student.age!!.year = 1000
        System.out.println(student.age)
    }
}