TIL what TIL means. Not really, but that is one of the TLA's I seem to have trouble remembering. Kind of like I know that PCMCIA doesn't mean People Can't Memorize Computer Industry Acronyms, but I can never remember what it really means.
Actually, what I really learned was more about Optional vs Nullable. I gained a deeper understanding of the advantages of Optional types. Not having to worry about NULL pointers can make things cleaner, easier to comprehend, and of course, avoid NPEs, which is always a good thing. Back when I was using Scala everything turned into a chain of operations on collections and without Optional that would have been a nightmare. With Optional things just seemed to flow.