[Misc] Document backport of invalidation counter in SecurityCache

Author: michitux

xwiki-platform-core/xwiki-platform-security/xwiki-platform-security-authorization/xwiki-platform-security-authorization-api/src/main/java/org/xwiki/security/authorization/cache/internal/SecurityCache.java

@@ -122,6 +122,7 @@ void add(SecurityShadowEntry entry, Collection<GroupSecurityReference> groups, l
      * security cache and then passed when adding the entry to the cache.
      *
      * @since 17.2.0RC1
+     * @since 16.10.9
      */
     long getInvalidationCounter();