export declare class DatetimeFormat {
    private static readonly DateFormat;
    private static readonly DatetimeFormat;
    private static readonly InvalidDate;
    static fixUTCDate(date: any): Date | null;
    static addTimeZoneOffset(dateWithoutTimeZoneOffset: any, isDateTime: boolean, returnInvalidDate?: boolean): string | null;
    static removeTimeZoneOffset(dateWithTimeZoneOffset: any, isDateTime: boolean, returnInvalidDate?: boolean): string | null;
    static zeroUtcOffset(date: any): Date | null;
    private static calculateTimeZoneOffset;
    private static isDefaultTimeZoneOffset;
    private static isValidDateTime;
}