The idea of an oviraptor being an eggeater came from a fossil that showed an oviraptor over some eggs, making it look like it was going to eat them. However, it was proven that the eggs were oviraptor eggs and the oviraptor was just taking care of them.
While an oviraptor could have eaten eggs, it probably was not its staple diet. It could have fed on smaller animals, like small mammals and lizards, or baby dinosaurs. I'm not sure if it was an omnivore or not, though. It could have been, thus eating perhaps berries or nuts or whatever else was available.
Besides we never really see any indication that Ruby and her kind are eggeaters, far as I know. With Srut and Ozzy's kind, we know this pretty much right away, almost. But I have yet to see any indication that Ruby and her kind are also eggeaters.