Correct method title. Add docblock

apps/files_versions/lib/backgroundjob/expireversions.php

@@ -74,7 +74,7 @@ class ExpireVersions extends \OC\BackgroundJob\TimedJob {
 				}
 				$isFSready = true;
 			}
-			Storage::expireOlderThan($uid);
+			Storage::expireOlderThanMaxForUser($uid);
 		}
 
 		\OC_Util::tearDownFS();

apps/files_versions/lib/storage.php

@@ -403,7 +403,11 @@ class Storage {
 		return $versions;
 	}
 
-	public static function expireOlderThan($uid){
+	/**
+	 * Expire versions that older than max version retention time
+	 * @param string $uid
+	 */
+	public static function expireOlderThanMaxForUser($uid){
 		$expiration = self::getExpiration();
 		$threshold = $expiration->getMaxAgeAsTimestamp();
 		$versions = self::getAllVersions($uid);