This release includes bug fixes, improvements and a few new features. QuickFIX/J now can accept UtcTimestamp fields with higher precision (up to picoseconds) and process timestamps up to nanoseconds precision. This is done using the Java8 DateTime API. Adaptations to your code might be necessary.
All QuickFIX/J users are invited to update their version.
Release notes can be found here: https://github.com/quickfix-j/quickfixj/wiki/QFJ-2.0.0-release-notes