To export from Dragon Bones, export from Dragon Bones to the latest Spine format. This actually produces a Spine JSON file that can be read perfectly by the engine.
Some example models are available in the DragonBones Demos repository. You can export them to Spine JSON and test now!
Copyright Michalis Kamburelis. Thanks go to Paweł Wojciechowicz from Cat-astrophe Games for various graphics. Even this documentation is open-source, you can redistribute it on terms of the GNU General Public License.