I have looked and there is no upgrade for javadoc plugin. A quick look at the root pom.xml commit history shows (commit 794ebd83f931c15c4343480cc393c5f2cc486416)
previous - <maven.archiver.version>3.4.0</maven.archiver.version> - <plexus.archiver.version>4.1.0</plexus.archiver.version> upgraded + <maven.archiver.version>3.5.0</maven.archiver.version> + <plexus.archiver.version>4.2.1</plexus.archiver.version> I suggest you try the older combination and see if it works (I had some other unrelated problems when trying to run 'mvn release:prepare' which stem from the fact I have never done this in the past and unfortunately I cannot spare the time right now to see what I am doing wrong). Note: you may have to also downgrade the JAR plugin to its previous version (see same commit) Hope this helps.
