[Go] Incorrectly generated time.Time type for models

Description

Go client/server generator excludes * for nullable/optional time.Time types. Because time.Time is a struct it will never get omitted from the models meaning that even if the time paramater is not set it will be sent with default values. omitempty works with primitives and pointers only.

Swagger-codegen version

swagger-codegen-cli-2.4.27.jar

Swagger declaration file content or url

swagger.json

Command line used for generation

java -jar swagger-codegen-cli-2.4.27.jar generate -i pet.json -l go -o go-client

Steps to reproduce

1. Execute the swagger-codegen-cli specified above.
2. Check the generated model_pet_dto.go

Related issues/PRs

#11791

Suggest a fix/enhancement

This and this templates need to be fixed.

Change from:

{{name}} {{^isEnum}}{{^isPrimitiveType}}{{^isContainer}}{{^isDateTime}}*{{/isDateTime}}{{/isContainer}}{{/isPrimitiveType}}{{/isEnum}}{{{datatype}}} `json:"{{baseName}}{{^required}},omitempty{{/required}}"{{#withXml}} xml:"{{baseName}}"{{/withXml}}`

to:

{{name}} {{^isEnum}}{{^isPrimitiveType}}{{^isContainer}}*{{/isContainer}}{{/isPrimitiveType}}{{/isEnum}}{{{datatype}}} `json:"{{baseName}}{{^required}},omitempty{{/required}}"{{#withXml}} xml:"{{baseName}}"{{/withXml}}`

Start with modules/swagger-codegen/src/main/resources/go/model.mustache and go-server/model.mustache, then reproduce the issue using swagger-codegen-cli-2.4.27.jar and the linked swagger.json. Inspect the generated model_pet_dto.go and verify that optional time.Time fields are represented and serialized correctly when unset.