[Java] Xchange me, sir - Sample REST project to get xrates to EUR

A while ago, while I was going through some interview rounds, a company that will be left unnamed, reluctantly assigned me a sample project to deliver as part of the interview process.
Very annoying though, was the fact that they had me book after some organisational pain, an hour of my time just to call and tell me in five minutes that it was highly unlikely I could deliver since I hadn't worked in Java recently.
Regardless of that quite bold and rude statement, I still asked to have the project just for practice anyway and they agreed, saying if I really wanted I could try and come back to them when I was done .
I of course did not plan to, but turning down some free exercise is never a smart choice, so I rolled with it.
Obviously they had never heard of Google as well, given that the whole project can easily be assembled just by searching code snippets and gluing them with minimal brainpower anyway if you are on a lazy mode day.
So long story short, here we are with the Xchange me, sir project.