API::checkAppToken PHP Method

    private function checkAppToken()
    {
        // check app token (if needed)
        if (!isset($this->parameters['app_token'])) {
            $this->parameters['app_token'] = "";
        }
        if (!($this->apiclients_id = array_search($this->parameters['app_token'], $this->app_tokens))) {
            $this->returnError(__("missing parameter app_token"), 400, "ERROR_APP_TOKEN_PARAMETERS_MISSING");
        }
    }