/**
 * Decorator that instructs the page router to add files to the list of files to be
 * protected by a content security policy that does not allow iframes outside of
 * Microsoft Teams.
 * The headers are added by the `MsTeamsPageRouter` Expreess router.
 * The following domains are allowd:
 * - teams.microsoft.com
 * - *.teams.microsoft.com
 * - *.skype.com *.sharepoint.com
 * - outlook.office.com
 * - and the current host
 * @param endpoint The Url
 */
export declare function PreventIframe(url: string): (target: any) => void;