* stable-2.13:
Metrics: Add missing Javadoc
Lifecycle{Manager,Module}: Add missing Javadoc
EventDispatcher: Add missing description on @throws javadoc
{ExtendedHttp,Http,Rpc}AuditEvent: Add missing @param javadoc tags
Fix formatting of links in Changes Submitted Together documentation
Fix usage of OutgoingEmailValidator to make sure TLD override works
Fix references to Guava classes from extension API Javadoc
GarbageCollectorListener: Replace direct link to external class
Prepare to render JGit references as links in api documentation
Allow to provide URLs for docs of external classes
Write each Lucene index using a dedicated background thread
Do not allow index futures to be cancelled
Change-Id: I9bc732562efa903ff201be86d9fb8ac2226ed8e5