I guess we just pay attention to whether there are any serious issues with releasing from JDK 11. So far I have heard about one relatively minor bug in Javadoc; and a Javadoc frameless mode which some people like and some people dislike (but the opinion of the plugin maintainer is not particularly relevant since they are unlikely to be the ones viewing their own Javadoc).
I guess we just pay attention to whether there are any serious issues with releasing from JDK 11. So far I have heard about one relatively minor bug in Javadoc; and a Javadoc frameless mode which some people like and some people dislike (but the opinion of the plugin maintainer is not particularly relevant since they are unlikely to be the ones viewing their own Javadoc).