Upgraded Eclipse, so now missing gwt-user jars

I have an existing Vaadin 6.8 project that was created using Eclipse Helios. Then I installed Eclipse Juno, but I am getting the following build error on that project:

Missing required library:…configuration\com.vaadin.integration.eclipse\download\gwt-user\2.3.0\gwt-user.jar

How do I get such dependencies (no doubt installed automatically by the vaadin eclipse plugin) to be re-installed on an existing Vaadin project?

EDIT: Found the fix. Just went to the project properties, Vaadin, and clicked the same vaadin 6.8.10 download and it seemed to then fix itself.