Actually, saying that good programers write parametric code may lead to complex code written by juniors. A rule of thumb I tend to teach juniors is that : - 1 copy paste is okay, - 2 is a sign of something wrong, - starting at 3 you must make your code generic.

But starting of with the generic formulation may lead to harder to understand production code.

And this is possible in Java since java 8 with [Optional] type and considered a good (modern) coding practice : https://docs.oracle.com/javase/8/docs/api/java/util/Optional.html

I would have thought that this came from Scala, another multi paradigm programming language, leaning towards functional programming. Functional programming as a time travelling machine !