How do I resolve ReactiveMongo 20.3 console warning?

Question

On updating from "org.reactivemongo" %% "play2-reactivemongo" % "0.16.6-play26" to "org.reactivemongo" %% "play2-reactivemongo" % "0.20.3-play27" I get the following warnings which I'm not sure how to handle.

package object json in package json is deprecated (since 0.19.2): Will be replaced reactivemongo.play.json.compat._ from reactivemongo-play-json-compat

I can't see anything that should affect this in the Play Framework update (2.6.4 to 2.7.4). Thanks for any pointers!