retrieveCurrent

Merge the currentAdministrativeUnitIndexFlow with administrativeUnitsFlow to receive the newly updated flow of the current AdministrativeUnit. Both flows are necessary because with the currentAdministrativeUnitIndexFlow, it's possible to get the currently selected AdministrativeUnit when the user selects one on the screen. And the administrativeUnitsFlow keeps sending changes that happen on that AdministrativeUnit in real-time while the user is on the administrative unit screen. It's guaranteed that the Flow only emits the object when there's a new change in it, for example, when a new Image is added. This Flow always emits the same instance of AdministrativeUnit for each index repeatedly. Therefore, you can't compare objects if they are the same instance. To verify if the object really changed its contents, its hash code is annotated. So, the next time this same object tries to emit, the hash code is compared to see if there was really a change, and it is emitted again only if its contents changed.