If the author means clojure.spec by "greenfield development" (I don't see what else he could mean) EDN, Transit, reducers, transducers, clojure.spec (I'm not

If the author means clojure.spec by "greenfield development" (I don't see what else he could mean) EDN, Transit, reducers, transducers, clojure.spec (I'm not saying any of these things are bad or anything, just pointing out that there was a lot of green field development done in the past few releases)