docs := openapi.OpenAPI{
  Version: "3.0.2",
  Info: openapi.Info{
    Title: "Cool service",
  },
  Paths: openapi.Paths{
    "/echo": openapi.PathItem{
      Post: openapi.Operation{
        Summary: "Scream into the void",
      },
    },
  },
}
jsonDocs, err := json.Marshal(docs)