[BUG] [go-server][golang] Trivial API file causes the generated code not to compile, due to missing imports "io" and "errors"

[Andrei-Errapart]

Description

The code generated doesn't compile, with the following error message:

go/api_silly_api.go:65:50: undefined: errors
go/api_silly_api.go:65:65: undefined: io

openapi-generator version

• 7.6.0
• 7.7.0
• 8.0.0-20240527.073301-5
  They all exhibit the same behaviour.

OpenAPI declaration file content or url

https://gist.github.com/Andrei-Errapart/8a7eeaf6744aad7409a054df6f7fc398

Generation Details

All default options.

Steps to reproduce

rm -rf sillyserver
mkdir -p sillyserver
java -jar $jar generate -i api-1.0.1.yaml -g go-server --output sillyserver || exit $?
cd sillyserver
go get || exit $?
go build . || exit $?

Related issues/PRs

#8847

Perhaps the same trick can be employed here: simply assign unused imports

Suggest a fix

Here is one recommendation: #8847 possible fix

The idea is to use to mark the imports as used and generate them always:

// Reference imports to suppress errors if they are not otherwise used.
var _ = proto.Marshal
var _ = fmt.Errorf
var _ = math.Inf

[RobQuistNL]

This is happening on 7.10.0 too.

EDIT:
Looks like they are kind of around in the templates;

openapi-generator/modules/openapi-generator/src/main/resources/go-server/controller-api.mustache

Lines 9 to 14 in 387fd99

	{{#isBodyParam}}
	{{^required}}
	"errors"
	"io"
	{{/required}}
	{{/isBodyParam}}

[RobQuistNL]

Still in 7.11.0

[JasperJuergensen]

Still having the issue in version 7.13.0.

What I noticed: The problem goes away if you set required to true on the requestBody (obviously only if it actually is required, but I think in most cases it will be; see OpenAPI 3.1 spec - Request Body Object), because then the !errors.Is(err, io.EOF) gets removed as well (so the import is no longer needed). But I am still not understanding why the imports are left out in the first place if required is false (which is the default), even though the error check is present (while having the same conditions).