Enum Schema is not referenced in Filter Schema

[GI-Ju]

I cannot explain this behavior. Is this intended or a bug? I've the follwing code:

class ContractType(enum.StrEnum):
    TYPE_1 = "Type 1"
    TYPE_2 = "Type 2"


class ContractTypeSchema(Schema):
    c_type: ContractType


class ContractSchema(Schema):
    x: int
    c_type: ContractType


class ContractFilterSchema(FilterSchema):
    c_type: ContractType
    c_type_list: List[ContractType]
    c_type_list_ref: List[ContractTypeSchema]


@api.get("/hello", response=ContractSchema)
def hello(request, filters: ContractFilterSchema = Query(...)):
    return "Hello world"

The curios behavior in the openapi is:

"ContractFilterSchema": { "properties": { "c_type": { "$ref": "#/components/schemas/ContractType" }, "c_type_list": { "items": { "enum": [ "Type 1", "Type 2" ], "title": "ContractType", "type": "string" }, "title": "C Type List", "type": "array" }, "c_type_list_ref": { "items": { "properties": { "c_type": { "$ref": "#/components/schemas/ContractType" } },

The property c_type_list is not referenced, it is written completely to the FilterSchema. Only if I put the ContractType enum into another Schema it is referenced... This leads to the problem in the client generator which loses the connection to the ContractType Component if it is not referenced in the FilterSchema.