How do I add a trait to all existing component types?

I want to go through all existing component types and add a trait to the model-> defaults and can't figure out how to do this. According to the documentation, I should be able to (in my plugin): But this overrides the traits array, which removes the existing traits, which isn't what I want. My next step was to try to get the old traits and concat them with my new ones - but I can't figure out how to pull the default traits for each type in order to do this. How can I append a trait to all (or some) component types?