@groostav Junior here. Shouldn't your junior have used a template ? So that he can call the same methods, without caring the object type ? Could you provide a version of what you would have done ? (Let me learn please =))
You should do code reviews and pair programming fixes with him, to let him learn. You have the experience, and if he's a little bit intelligent, he knows it, and may want to take advantage of this in order to learn more and more about clean code 😃
I remember my first code review with a Senior dev in internship. He bullshited my code and me in the same way, but took time to show me how I could have done the work. Best lesson in my life