Having the proper Eclipse Java editor instead of the old style editor was introduced in 8.5.1, but there was one huge annoyance. When you edited a Java file, you had to save that, but then also remember to save the agent as well. Cue plenty of swearing and head scratching when your change wasn't showing up.
Well in 8.5.2 there is a new preference setting which allows the agent to be automatically saved when you save the Java file:
Just check the "Autosave Java design element on save of individual Java sources" box to make your Java coding a lot less annoying.