import { ValidationOptions, ValidationResult } from "./type";
export declare class _Undefined {
    /**
     * Check if the given object is undefined or null.
     * @param obj Object to check
     * @returns boolean
     */
    static isUndefined<T>(obj: T): boolean;
    /**
     * Checks if the given object is undefined or null, and returns a default value if so.
     * @param obj The Object to check
     * @param returnValue The value to return if the object is undefined or null
     * @returns returnValue` if `obj` is undefined or null, otherwise returns `obj
     */
    static defaultIfUndefined<T, K>(obj: T | undefined | null, returnValue: K): NonNullable<T> | K;
    static setDefaultIfUndefined<T>(obj: T | undefined | null, defaultValue: Partial<T>): T;
    /**
     * This function return the first property it found to be undefined or null.
     * If the object itself is undefined or null, it will return true.
     *
     * @description
     * This function is useful when you want to check if an object has any property that is undefined or null, without having to check each property individually.
     * @param obj Object to check Record<string, any>
     * @returns boolean
     */
    static isUndefinedOrNull(obj: any, label?: string, options?: ValidationOptions): ValidationResult;
    static validate(obj: any, label?: string, options?: ValidationOptions): void;
    private static collectIssues;
    private static findFirstMissing;
}
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