This release of dyn4j is a small maintenance release to fix a bug introduced in 3.1.3. With this some flip methods have been added to the Geometry class to allow flipping of polygons about arbitrary axes and points.
This release should not contain any breaking changes unless you were using or storing shape, fixture, body, joint, etc. ids. These ids were of type String, but have been changed to UUID for performance (they were actually UUID.toString() anyway). You can still get the old String value by getId().toString().
No new release of the Sandbox was published for this release.