(submitted prematurely; text below should be in the description)
I was trying to upgrade my old E3.6 + GRE 2.0.2, but it refused to upgrade, so I went for a clean install of latest release Eclipse JEE 3.7.1 and GRE 2.5.1. They don't seem to play nicely however. It all installed fine, but when I went to open a *.groovy file (in the Groovy editor) it started complaining:
Creating a new Groovy project is okay, but creating a new Groovy class gives:
java.lang.ClassCastException: org.eclipse.jdt.internal.core.CompilationUnit cannot be cast to org.codehaus.jdt.groovy.model.GroovyCompilationUnit
Digging around there was also an error thrown in bundle activation (for refactoring):
org.osgi.framework.BundleException: Exception in org.codehaus.groovy.eclipse.refactoring.Activator.start() of bundle org.codehaus.groovy.eclipse.refactoring
Caused by: java.lang.ClassNotFoundException: org.codehaus.jdt.groovy.integration.LanguageSupport
Everything is set to use JDK 6 and Groovy 1.8 – no 7's lying about anywhere that I can see, so I don't think this is quite the same as the Java7 issues – although my guess would be they've changed JDT code and the patch no longer is getting activated?