how to use a custom schema definition?

[Omarabdul3ziz]

i faced an issue while trying to register this service to my API and create the docs for it

The service

type Cal struct{}

type PlusArg struct {
	Num int
}

type PlusReply struct {
	Num int
}

func (c *Cal) Plus(arg *PlusArg, reply *PlusReply) error {
	ans := arg.Num + 1
	reply.Num = ans
	return nil
}

The error

json: error calling MarshalJSON for type openrpc_document.ContentDescriptorOrReference: json: error calling MarshalJSON for type *openrpc_document.JSONSchema: json: error calling MarshalJSON for type *openrpc_document.JSONSchema: failed to marshal any one of the object properties

I noticed this section on the docs https://github.com/etclabscore/go-openrpc-reflect/blob/master/README.md#library-limitations but the link to using a custom schema is just a TODO https://github.com/etclabscore/go-openrpc-reflect/blob/master/README.md#TODO

any help please about what should i do?