BackendlessAPI.Engine.HeadersManager.GetInstance C# (CSharp) Method

        public static HeadersManager GetInstance()
        {
            if (_instance == null)
            {
                lock (headersLock)
                {
                    if (_instance == null)
                    {
                        _instance = new HeadersManager();
                        _instance.AddHeader( HeadersEnum.APP_ID_NAME, Backendless.AppId );
                        _instance.AddHeader( HeadersEnum.SECRET_KEY_NAME, Backendless.SecretKey );
                        _instance.AddHeader(HeadersEnum.APP_TYPE_NAME, "WP");
                        _instance.AddHeader(HeadersEnum.API_VERSION, "1.0");
                       
                    }
                }
            }

            return _instance;
        }

        public static void InvokeAsync <T>(string className, string methodName, object[] args, bool enableUnderFlowInspection, AsyncCallback <T> callback)
        {
            var responder = new Responder <T>(response =>
            {
                if (callback != null)
                {
                    callback.ResponseHandler.Invoke(response);
                }
            }, fault =>
            {
                var backendlessFault = new BackendlessFault(fault);
                if (callback != null)
                {
                    callback.ErrorHandler.Invoke(backendlessFault);
                }
                else
                {
                    throw new BackendlessException(backendlessFault);
                }
            });

            try
            {
                ResponseThreadConfigurator responseConfig = null;

                if (enableUnderFlowInspection)
                {
                    responseConfig = new ResponseThreadConfigurator(SetupUnderFlowListener);
                }

                client.Invoke <T>(className, methodName, args, null, HeadersManager.GetInstance().Headers, responder, responseConfig);
            }
            catch (System.Exception ex)
            {
                var backendlessFault = new BackendlessFault(ex.Message);
                if (callback != null)
                {
                    callback.ErrorHandler.Invoke(backendlessFault);
                }
                throw new BackendlessException(backendlessFault);
            }
        }