Optional parameters being sent as encoded

[davemackintosh]

I have a route defined as

{
  method: "GET",
  path: `/${model_name}/{id?}`,
  config: {
    handler: Functions.GET.bind(models[model_name]),
    description: `Get a paginated list of "${model_name}"`,
    notes: `Return a list of "${model_name}" in the database. If an ID is passed, return matching documents.`,
    tags: ["api", model_name],
    validate: {
      params: Joi.object({
        id: Joi.string().optional().description(`ID of the ${model_name} to get`)
      })
    },
    response: {
      schema: Joi.array().items(reply_joi)
        .meta({
          className: `Get ${model_name}`
        })
    }
  }
},

But the UI shows the ID without the optional flag ? and sends the request as %7Bid%7D