Should we use/encourage HTTP 422 for validation failures?

[benjie]

https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Status/422
https://github.com/graphql/graphql.github.io/pull/2006/files

(Specifically for when the syntax is valid (parse succeeds) but validation fails.)

[enisdenjo]

I am always in favour following HTTP conventions.