Improvements for OSGi support in Vaadin

Hi,

I've spent the last weeks trying to run Vaadin in an OSGi environment. The current support for OSGi seems to be broken or only working in very specific settings (see here).
Therefore, I developed my own integration that is currently working with Vaadin 8.2.1(see here)
During the development of this integration I also had a look at the current OSGi integration regarding Themes/Widgetsets/Resources which could also be enhanced. A first draft of this enhancement could be seen here

What are those enhancements good for?

• No more need in core Vaadin to explicitly call VaadinResourceServiceImpl nor any dependencies to OSGi in the core Vaadin bundles. If you want Vaadin to be OSGi compatible all you will have to do is to add an additional bundle to your runtime.
• UIs will be Declarative Services that can have their own references to other OSGi components/services. The lifecycle of UIs is managed so that all dependencies are resolved before init() is called.
• New themes/widgetsets/resources can be made available by adding just one line to the manifest (currently a call to a static method of VaadinResourceServiceImpl is required and this only works if the bundles are started in the right order )

Is this an enhancement that you would like to see in the framework? Or do you have any plans on your own regarding enhancing OSGi support in Vaadin that I'm not aware of?

If this is an enhancement you'd like to see I would prepare a pull request for this and rewrite my solution in Java (currently written in Xtend).

Kind regards,
Thomas

Start by reviewing the existing OSGi support in Vaadin and the proposed integration linked in the issue, especially OSGiResourceExtender.xtend. Compare that approach with the reported Vaadin 8.2.1 behavior and the forum discussion. The issue needs a decided scope and acceptance criteria before implementation can be considered done.