apply method of FieldExtension not executed on Input fields

[stygmate]

apply method of FieldExtension don't seem to be executed by schema_converter for fields of inputs.

[erikwrede]

Hey @stygmate, the FieldExtension feature is currently meant as a way to modify the behavior of any field in the GraphQL API. Since input fields are more of a data holder and don't have resolvers, we don't take them into account.

I'm curious though: what is your intended use case? Maybe we can make the case for input field extensions as well.