[BUG][GO] Some errors with `oneOf` type

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
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Description

We are generating client specs for go using 5g 3gpp swagger specs found here (https://raw.githubusercontent.com/jdegre/5GC_APIs/master/TS29522_TrafficInfluence.yaml)

java openapi-generator-cli-6.0.0.jar generate -i https://raw.githubusercontent.com/jdegre/5GC_APIs/master/TS29522_TrafficInfluence.yaml -g go -o ./client_trafficInfluence

Running gofmt you will see the files have some errors

gofmt -s -w .

specs/client_trafficInfluence/model_ip_addr.go:20:11: expected type, found '{'
specs/client_trafficInfluence/model_ip_addr.go:25:2: expected declaration, found 'return'
specs/client_trafficInfluence/model_ip_addr.go:34:2: expected declaration, found match
specs/client_trafficInfluence/model_route_to_location.go:20:2: expected '}', found 'interface'
specs/client_trafficInfluence/model_route_to_location.go:27:2: expected declaration, found 'if'

For example the type Interface{} is used twice on the definition. While t should define a sere of properies.

// IpAddr - Contains an IP adresse.
type IpAddr struct {
	Interface{} *interface{}
}

// interface{}AsIpAddr is a convenience function that returns interface{} wrapped in IpAddr
func Interface{}AsIpAddr(v *interface{}) IpAddr {
	return IpAddr{
		Interface{}: v,
	}
}

This is how it should look like (extracted from the server case)

// IpAddr - Contains an IP adresse.
type IpAddr struct {

	// String identifying a IPv4 address formatted in the 'dotted decimal' notation as defined in RFC 1166.
	Ipv4Addr string `json:"ipv4Addr,omitempty"`

	Ipv6Addr Ipv6Addr1 `json:"ipv6Addr,omitempty"`

	Ipv6Prefix Ipv6Prefix `json:"ipv6Prefix,omitempty"`
}

openapi-generator version

6.0.0

Generation Details

java openapi-generator-cli-6.0.0.jar generate -i https://raw.githubusercontent.com/jdegre/5GC_APIs/master/TS29522_TrafficInfluence.yaml -g go -o ./client_trafficInfluence

Steps to reproduce

Just run that command and it will generate the files

Related issues/PRs

https://github.com/OpenAPITools/openapi-generator/issues/12955

Suggest a fix

Run the listed openapi-generator 6.0.0 command against TS29522_TrafficInfluence.yaml and inspect the generated model_ip_addr.go and model_route_to_location.go files. Compare the generated oneOf models with the shown server-side IpAddr shape; done means the Go output represents the properties correctly and passes gofmt without syntax errors.