g-leaflet is a fresh start for GWT API for Leaflet. Integration should become lightweight using javascript overlays, but with small compromises with to API. Hoping this project to be/become as simple and clean as Leaflet itself.
There is also Leaflet.Draw API: https://github.com/mstahv/g-leaflet-draw
Releases available via Vaadin Directory: https://vaadin.com/directory/
A small usage example and test project available at: https://github.com/mstahv/gleafletexample
When using library, developer must first call LeafletResourceInjector.ensureInjected() (XSLinker compatible!) that will injects required resources to your apps host page.
Things should also work if one includes Leaflet into host page in other manners.
Manual and JavaDocs are not yet available (pathes wellcome!). API should mimic actual Leaflet API quite a lot. Some hints can also taken from v-leaflet project (Vaadin Leaflet integration), that has defined the initial feature set. Code for it might be in a branch initially.