ROS 2 common interfaces (default message types and Euclid type support) are now included with the library artifact. This is done so publishers and subscribers for the DDS common types including Euclid types can be created without external code/tricks.
ROS2Publisher and QueuedROS2Publisher now have improved error output and exception handling
Empty classes RealtimeROS2Publisher and RealtimeROS2Subscription have been removed. They weren't actually providing realtime functionality.
ROS2Callback is now deprecated. You should use ROS2NodeInterface#createSubscription2 instead.
APIs have been filled in to include ROS2Topic
Creating nodes, publishers, and subscribers no longer throws IOException. This wasn't useful and just made the library frustrating to use.
Quality of service (QoS) is now a setting of ROS2Topic. Each topic should define it's own QoS.
RELIABLE is now an explicitly named ROS2QoSProfile option.
DEFAULT quality of service (QoS) is now BEST_EFFORT instead of RELIABLE to help alleviate comms issues. This is only used if the topic does not specify the QoS to use. The default QoS can be set with the ROS_DEFAULT_QOS environment variable.
The DEFAULT_NAMESPACE is now accessible via the public field in ROS2NodeBasics.