/**
 * Validated environment variables served by `ConfigService#get`, one layer
 * per `ConfigModule.forRoot()` call. A layer holds the validator's output as
 * is, so that the members of a class instance it returns keep working.
 */
export declare class ValidatedEnv {
    private readonly layers;
    add(values: Record<string, any>, hiddenKeys: Set<string>, convertedKeys: Set<string>): void;
    /**
     * Resolves a property path. "found" with an `undefined` value means that
     * the validator removed the variable.
     */
    resolve(path: PropertyKey): {
        found: boolean;
        value: unknown;
    };
    /**
     * Replaces the value of a variable that is a string (a value converted by
     * validation, e.g. to a number, is not replaced, it isn't validated again).
     * The variable name is used as is, never as a path.
     */
    update(key: string, value: string): void;
    /**
     * Returns the layers that may serve a path, in the order they are tried:
     * the ones that converted it (the last first), then all of them in the
     * order they were added. So a value a validator only passed through (e.g.
     * the raw form of a variable another validator converted) doesn't replace a
     * converted one.
     */
    private getLayers;
}