Getting ng-options value from Map in Apache Zeppelin

Question

I am trying to populate select using ng-otions from HashMap. I don't get anything out

I tried this, but it does not work. However, it works with a String array

<select ng-model="group" ng-options="key for (key, g) in groups"></select>

I checked the angular binding and everything is in place.

As a backup, I created an array of separable strings, but then I cannot split each row into a key and value