Upgrade to Java-Utils 4.0.0; upgrade other dependencies

In this release, I upgraded to the latest release of Java-Utils (version 4.0.0). I also upgraded several other dependencies.
NOTE: This is a major-version release due to the major-version bump in the Java-Utils dependency.

I migrated away from gpg credentials stored in my Maven settings and fully over to gpg-agent.
I also added a missing JavaDoc entry to resolve a warning.