response_or_reference ref is not generated correctly

Hey there,
So I have this in my proto file:
```
responses: {
response_or_reference: {
name: "default"
value: {
response: {
content: {
additional_properties: [{
value: {
schema: {
reference: { _ref: "#/components/schemas/ErrorResponse"; }
}
}
}]
}
}
}
}
}
```

and
```
message ErrorResponse {
string message = 1 [(google.api.field_behavior) = REQUIRED];
}
```

ErrorResponse is being generated into go code, but when I run protoc with openapi ErrorResponse is not being added to components (it's not being used anywhere besides the code above)
Is there any way to force openapi generator to add all structs into the components?

Thanks!