After experiencing the problem described at:
https://bugs.eclipse.org/bugs/show_bug.cgi?id=488703
I determined that it's the Groovy Eclipse plugin fault. Substantially, it seems like it's carrying in some old JDT code that is being used instead of the one updated with Mars.1 and Mars.2.

I know this plugin is not maintained any more, but could at least a newer version be packaged, based on Mars.2 JDT? Thank you.