* Generate a purely relative timestamp, i.e., represent the time elapsed between
* the given base timestamp and this object.
*
- * @param MWTimestamp $relativeTo Relative base timestamp (defaults to now)
- * @param User $user Use to use offset for
- * @param Language $lang Language to use
+ * @param MWTimestamp|null $relativeTo Relative base timestamp (defaults to now)
+ * @param User|null $user Use to use offset for
+ * @param Language|null $lang Language to use
* @param array $chosenIntervals Intervals to use to represent it
* @return string Relative timestamp
*/