In this case we have just a list of values, an hashmap will looks like:

```js
    const SHEET_TYPE = {"agent": true, "user": true, "author": true};
```

instead of just simply:
```js
   const SHEET_TYPE = ["agent", "user", "author"];
```

I don't see a value here to have an hash map, when we have formally a list. I would prefer keep the array, also it's what we use in other places for the same purpose (see `attachTo` in PageMod)