/**
 * Utility to get environment variables from a list of possible keys.
 *
 * E.g. you may want to check if there is an environment variable defined for PORT or SERVER_PORT.
 */
export declare class ProcessEnvUtils {
    /**
     * Gets the environment variables
     * @param defaultValue
     * @param {string} possibleKeys
     * @returns {any}
     */
    static getEnvVar(defaultValue: any, ...possibleKeys: string[]): any;
    static getEnvVarAsBoolean(defaultValue: boolean, ...possibleKeys: string[]): boolean;
    static getEnvVarAsString(defaultValue: string, ...possibleKeys: string[]): string;
    static getEnvVarAsNumber(defaultValue: number, ...possibleKeys: string[]): number;
}