I am a quite in shock. I have tried to update grails-vaadin plugin so I could use the new version of Vaadin 7.0.0alfa3 together with Grails 2.1.0. But what a surprise... alfa3 contains a bit more classes than previous version and it makes it imposible to integrate Vaadin 7.0.0 alfa3 with Grails 2.1.0.
Have a look how size of Vaadin jars increased...
What does it mean. When I try to add com.vaadin:vaadin:7.0.0.alpha3 as dependency then Grails fails to load with the following error:
Error Interactive mode exited with error: loader constraint violation: when resolving method "javax.xml.parsers.SAXParser.getXMLReader()Lorg/xml/sax/XMLReader;" the class loader (instance of org/codehaus/groovy/grails/cli/support/GrailsRootLoader) of the current class, groovy/util/XmlSlurper, and the class loader (instance of <bootloader>) for resolved class, javax/xml/parsers/SAXParser, have different Class objects for the type org/xml/sax/XMLReader used in the signature.
I have already complained about it http://dev.vaadin.com/ticket/9180. Let's see what happens with the next releases. I still hope it is a kind of a bug or bad joke that there are so many libraries included in the package.
Here you can find working version of Vaadin 7 (alfa2) for Grails (it is still experimental version, but it worked for few people already): https://github.com/ondrej-kvasnovsky/grails-vaadin-plugin/downloads.