[BUG] [go-server] Error building generated server with example petstore.yaml

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• What's the version of OpenAPI Generator used?
• Have you search for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Bounty to sponsor the fix (example)

Description

I tried to test the server code generated in Go using the example petstore.yaml provided in https://github.com/OAI/OpenAPI-Specification/blob/master/examples/v3.0/petstore.yaml

The generation command I used is

docker run --rm \
    -v $PWD:/local openapitools/openapi-generator-cli generate \
    -i /local/petstore.yaml \
    -g go-server \
    -o /local/go_server

After code generation, trying to run the server by go run main.go failed with error below

go/api_pets.go:13:2: imported and not used: "encoding/json"
go/api_pets.go:69:35: cannot use limit (type string) as type int32 in argument to c.service.ListPets

openapi-generator version

The docker cli openapitools/openapi-generator-cli

OpenAPI declaration file content or url

The yaml is the official example petstore.yaml in https://github.com/OAI/OpenAPI-Specification/blob/master/examples/v3.0/petstore.yaml

Command line used for generation

docker run --rm \
    -v $PWD:/local openapitools/openapi-generator-cli generate \
    -i /local/petstore.yaml \
    -g go-server \
    -o /local/go_server

Steps to reproduce

1. Run the code generation command
2. cd go_server
3. go run main.go

Related issues/PRs

Suggest a fix

Start by running the Docker generation command with the official petstore.yaml, then inspect the generated go/api_pets.go and main.go files. Reproduce the failure with go run main.go and trace the reported unused import and ListPets argument errors. Done means the generated Go server builds and runs without these compiler errors.