#[0]$ cat config.yaml2
package: preferskipoptionalpointerwithomitzero
output: gen.go
generate:
  models: true
output-options:
  skip-prune: true

#[0]$ cat spec.yaml2
openapi: "3.0.0"
info:
  version: 1.0.0
  title: testing
components:
  schemas:
    ClientWithExtension:
      type: object
      properties:
        newfield:
          type: string
          nullable: true

#[0]$ oapi-codegen --config config.yaml2 spec.yaml2

#[0]$ cat gen.go
// Package preferskipoptionalpointerwithomitzero provides primitives to interact with the openapi HTTP API.
//
// Code generated by github.com/oapi-codegen/oapi-codegen/v2 version v2.5.0 DO NOT EDIT.
package preferskipoptionalpointerwithomitzero

// ClientWithExtension defines model for ClientWithExtension.
type ClientWithExtension struct {
        Newfield *string `json:"newfield"`
}

#[0]$ oapi-codegen --version
github.com/oapi-codegen/oapi-codegen/v2/cmd/oapi-codegen
v2.5.0

#[0]$ go version
go version go1.24.4 linux/amd64