The GraphQL community has proposed a new built-in directive called `@oneOf` to improve schema expressiveness, allowing input types to indicate that one and only one of the fields must be provided. This can be applied to input types to provide more precise contract representation, making it easier for clients to query APIs with different criteria. The proposal aims to enhance the GraphQL standard by introducing a new directive that doesn't introduce any new syntax and is backwards compatible with existing client libraries. With this feature, Apollo Kotlin and Apollo Server now support `@oneOf` in their latest versions, allowing developers to try it out and provide feedback on the proposed RFC.