headers["Authorization"] = "Basic " . $environment->authorizationString(); $body = [ "grant_type" => "client_credentials" ]; if (!is_null($refreshToken)) { $body["grant_type"] = "refresh_token"; $body["refresh_token"] = $refreshToken; } $this->body = $body; $this->headers["Content-Type"] = "application/x-www-form-urlencoded"; } }