Language injections in JSON

Hello,

I've configured a few language injections but I just cannot figure out how to define a language - in this case VTL - for a JSON attribute.   This type of scenario is quite common in the products I work with.  I can manually assign an injection to an attribute value but it goes away when the file is closed.  How can I configure IntelliJ to automatically assign a particular JSON property as containing an other language?

Any help appreciated.  The JS language injections don't really seem to work.

Thanks,

gp