As noted in a recent readme commit, currently the 3.0 schema is supported.
As a remedy, I found the pythonic openapi-downgrade to be usable. You might still need to hand-edit the input OpenAPI 3.1 spec so the output OpenAPI 3.0 schema passes the validation (but at least it performs validation). YMMV (well, my as well, at this point).
Edit: I needed some additional change in the downgrade tool (see RajeshRoy4426/openapi_downgrade_3_0#4) to avoid this codegen emitting plain Aeson.Object for the singleton-allOf-wrapped $refs, which the OpenAPI 3.1 type: [{"$ref":...}, "null"] ended up without the change after downconversion)
As noted in a recent readme commit, currently the 3.0 schema is supported.
As a remedy, I found the pythonic openapi-downgrade to be usable. You might still need to hand-edit the input OpenAPI 3.1 spec so the output OpenAPI 3.0 schema passes the validation (but at least it performs validation). YMMV (well, my as well, at this point).
Edit: I needed some additional change in the downgrade tool (see RajeshRoy4426/openapi_downgrade_3_0#4) to avoid this codegen emitting plain Aeson.Object for the singleton-allOf-wrapped $refs, which the OpenAPI 3.1
type: [{"$ref":...}, "null"]ended up without the change after downconversion)