I have no idea how that could be implemented using B4J syntax. Using this in Javascript even gives me problems:
_obj = {
locales: { zhHans, pl, sv }
}
console.log(_obj);
-> zhHans is undefined.
Which makes sense, as this object is somehow a definition of an object, but not an instance of anything.
Must be a weird Vue construction. Maybe (or maybe not) you can do it with inline javascript.