I don't like the word "flatten"

[ryanjjung]

Plain and simple, that's what that function does, but it's not how I want to think about it. This should just be a cached property called resources. It makes so much more sense that you have a single Resource and a collection of resources in a ThunderbirdCompositeResource or in a ThunderbirdPulumiProject.

Let's maybe keep/deprecate the flatten function, replacing it with a cached property called resources.