It is not obvious from the documentation that FixedVaadinServlet name cannot be changed.

[johannest]

If trying to change the name "FixedVaadinServlet" to anything else (in https://github.com/vaadin/base-starter-flow-karaf), push fails to load. There are the following errors in the browser's console:

Uncaught SyntaxError: Unexpected token '<'
...
vaadin-5-1ca1eb43b4ae79ad0352.cache.js:1 http://localhost:8181/VAADIN/static/push/vaadinPush.js could not be loaded. Push will not work.
...

How to fix: mention in the Apache Karaf documentation (https://vaadin.com/docs/latest/flow/integrations/osgi/#osgi.servlet) that the FixedVaadinServlet's name should not be changed.

[tarekoraby]

Are we certain that this is not a bug in our Karaf implementation?

[jouni]

We could document it as a feature until we know better. If it turns out to be a bug, we can update the docs to point to the issue.

[tarekoraby]

I think we'd be better off confirming that it's not a bug before documenting it.

[jouni]

Who knows about our Karaf integration? @mshabarov perhaps? Is this a bug?

[mcollovati]

It seems like some kind of bug in the OSGi add-on or in the starter. Servlet rename worked for me on several attempts, but seldom I got an exception during startup and the push script was not loaded, even with the original servlet name.

The error is a class cast with a lambda exception.

Caused by: java.lang.ClassCastException: Cannot cast com.vaadin.flow.osgi.support.OSGiVaadinInitialization$$Lambda$1098/0x00000008014487c8 to com.vaadin.flow.internal.VaadinContextInitializer
	at java.lang.Class.cast(Class.java:3889) ~[?:?]
	at com.vaadin.flow.server.VaadinServletContext.getAttribute(VaadinServletContext.java:76) ~[?:?]
	at com.vaadin.flow.server.VaadinContext.getAttribute(VaadinContext.java:58) ~[?:?]
	at com.vaadin.flow.server.VaadinServlet.initializeContext(VaadinServlet.java:614) ~[?:?]
	at com.vaadin.flow.server.VaadinServlet.init(VaadinServlet.java:110) ~[?:?]
	at com.vaadin.flow.osgi.support.servlet.OSGiVaadinServlet.init(OSGiVaadinServlet.java:76) ~[?:?]
	at org.ops4j.pax.web.service.spi.servlet.OsgiInitializedServlet.init(OsgiInitializedServlet.java:68) ~[?:?]
	at org.eclipse.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:632) ~[?:?]
	at org.eclipse.jetty.servlet.ServletHolder.getServlet(ServletHolder.java:486) ~[?:?]
	at org.eclipse.jetty.servlet.ServletHolder.prepare(ServletHolder.java:759) ~[?:?]
	at org.ops4j.pax.web.service.jetty.internal.PaxWebServletHolder.prepare(PaxWebServletHolder.java:295) ~[?:?]
	at org.ops4j.pax.web.service.jetty.internal.PaxWebServletHandler.doHandle(PaxWebServletHandler.java:306) ~[?:?]
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143) ~[?:?]
	at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:600) ~[?:?]
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127) ~[?:?]
	at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:235) ~[?:?]
	at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1624) ~[?:?]
	at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:233) ~[?:?]
	at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1440) ~[?:?]
	at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:188) ~[?:?]
	at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:505) ~[?:?]
	at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1594) ~[?:?]
	at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:186) ~[?:?]
	at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1355) ~[?:?]
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141) ~[?:?]
	at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:191) ~[?:?]
	at org.ops4j.pax.web.service.jetty.internal.PrioritizedHandlerCollection.handle(PrioritizedHandlerCollection.java:96) ~[?:?]

[mcollovati]

Another issue seems to be that if you rename the servlet and do not clean the project mvn clean, the old servlet service descriptor will still be in the jar file, and this prevents the bundle to be loaded correctly