/**
 * Makes a deep copy of the object including a copy of all the children and so on.
 * @param source source object. It can be any type
 * @param fields list of root fields that should be copied. If not sent, it will copy all the fields.
 * Note: the fields only filters the children of the source not the grandchildren.
 */
export declare function deepCopy<T>(source: T, fields?: string[]): T;