Version 2.16.0 is available upstream. Please consider updating! It seems that version 2.16.0 is available upstream, while the latest version in the Gentoo tree is 2.15.0. You think this warning is false? Read more about it here.
ATD stands for Adaptable Type Definitions. It is a syntax for defining
cross-language data types. It is used as input to generate efficient and
type-safe serializers, deserializers and validators.