I do frequently find that Spring documentation reads more like a novel than it does technical documentation. I find you can sometimes take many minutes, or even hours, just wading through stuff to find out how to do something that should have taken 5-10 minutes. Spring's REST framework is relatively straight forward to use, but there doesn't seem to be a good quick start on it's use.
So, we endeavour to have you up and running with their "Building a RESTful Web Service" tutorial in under 5 minutes, assuming you have a basic java development environment going, meeting their requirements. Please quickly review the first two "What you'll build" and the "What you'll need" sections at "Building a RESTful Web Service", then come back here.
We have one additional requirement. It's assumed you're able to develop from a Linux command line. If you're not using Linux as a development platform, you really should be.
We won't be using gradle, as I personally think it's a really bad tool.