This http://www.gwtproject.org/doc/latest/DevGuideCodingBasicsCom... seems to indicate that GWT still supports only Java 1.5. Is this true or simply outdated documentation?
Parts of the page are still rather outdated and haven't really been touched since 2010/ 2012.
This is why it's so great that the site got a new look now, it indicates that things are moving again and I'm sure the outdated parts are going to be removed soon.