Swift TRON内容类型HeaderBuilder语法

我正在使用TRON来访问基于ruby on rails的api，我觉得我的问题是因为标题没有正确的信息。 我一直在使用TRON的HeaderBuilder语法，但却无法真正看到语法需要的内容。 我的rails错误是在尝试从特定控制器操作获取数据时

[active_model_serializers] Rendered ActiveModel::Serializer::Null with Hash (0.25ms) Filter chain halted as :ensure_valid_accept_media_type rendered or redirected Completed 406 Not Acceptable in 61ms (Views: 30.0ms | ActiveRecord: 2.7ms | Solr: 0.0ms) 

在xcode中，我使用rest类型控制器来获取json

 public class DataController { static let tron = TRON(baseURL: GlobalVariables().baseURL) class Fetched: JSONDecodable { let response: JSON required init(json: JSON) throws { let response = json self.response = response } } class FetchFailed: JSONDecodable { let response: JSON required init(json: JSON) throws { let response = json self.response = response } } func FetchData(url_param: String) { let FetchRequest: APIRequest = DataController.tron.request(url_param) FetchRequest.perform(withSuccess: { (Fetched) in print("Success", Fetched) }) { (err) in print("Error") } } func Get(parameters: [String:Any], path: String) -> APIRequest { let request: APIRequest = DataController.tron.request(path) request.parameters = parameters request.headerBuilder.headers(forAuthorizationRequirement: AuthorizationRequirement.allowed, including: ["Accept":"application/vnd.api+json"]) return request } 

我在方法中添加了headerbuilder调用，但我认为我还需要内容类型。 我已经在这上面花了一天时间，需要弄清楚不要错过最后期限:(提前感谢任何帮助