Git Ignore All Files of a Certain Type, Except Those in a Specific Subfolder

I have a directory structure like this:

• root
  • folder1
    • abc.json
    • def.json
    • somedir
      • more.json
  • folder2
    • qwe.json
    • rty.json
  • spec
    • mock1.json
    • mock2.json
    • somedir
      • more_mocks.json

Now using a .gitignore I want to ignore all *.json files except for the ones in the spec. I don't want to use a .gitignore in folder1 and folder2 because there are a ton of these and they will get added to a lot, and I'm sure I will forget to move the right .gitignore file in place.

In addition, there may be more nested directories with JSON files, and this rule needs to apply to all subdirectories as well.

So how do I ignore all files of a type, except for a certain subdirectory?