[ticket/12536] Get Versions Should Not Require Both Stable and Unstable
* Nicofuma/ticket/12536:
[ticket/12536] Restore missing @throws
[ticket/12536] Add test cases with empty versions list
[ticket/12536] Use stable values when unstable are unavailable
[ticket/12536] Update doc block
[ticket/12536] Return empty array if stability unavailable
[ticket/12536] Get Versions Should Not Require Both Stable and Unstable