I use Eclipse with Vaadin 8 and Vaadin Designer. In the Source mode view of the Vaadin designer, i get warning for all my Vaadin Elements. It is not a problem for the system but it is annoying to see these warnings all the time. I have added a shreenshot. How do I resolve these warnings?
The easiest way is just right click the editor and go preferences / web / validation. Select what you want to do with "Unknown tag name", e.g. ignore. You can set this for specific project, if you need html validation in other projects.