Adding anything other than generic types doesn't type check on key-map objects
Example:
/**
* @typedef {"MARKET1"|"MARKET2"|"MARKET3"} Market
* @typedef {{
name: string,
}} Item
this type checks just items, not keys
* @typedef {{
items: Object.<string, Item[]>,
}} Config
this doesn't type check anything, even items
having a non generic type in the key field doesn't raise any error
* @typedef {{
items: Object.<Market, Item[]>
}} Config
*/

