/** Http method type definition. */
export type HttpMethod = 'GET' | 'POST' | 'PUT' | 'DELETE' | 'PATCH' | 'HEAD';
/** API callback function type definition. */
export type ApiCallbackFunction = (data: object) => void;
/**
 * Class that defines all the settings for the backend API endpoint.
 *
 * @param endpoint - The Firebase Auth backend endpoint.
 * @param httpMethod - The http method for that endpoint.
 * @constructor
 */
export declare class ApiSettings {
    private version;
    private endpoint;
    private httpMethod;
    private requestValidator;
    private responseValidator;
    constructor(version: 'v1' | 'v2', endpoint: string, httpMethod?: HttpMethod);
    /** @returns The backend API resource version. */
    getVersion(): 'v1' | 'v2';
    /** @returns The backend API endpoint. */
    getEndpoint(): string;
    /** @returns The request HTTP method. */
    getHttpMethod(): HttpMethod;
    /**
     * @param requestValidator - The request validator.
     * @returns The current API settings instance.
     */
    setRequestValidator(requestValidator: ApiCallbackFunction | null): ApiSettings;
    /** @returns The request validator. */
    getRequestValidator(): ApiCallbackFunction;
    /**
     * @param responseValidator - The response validator.
     * @returns The current API settings instance.
     */
    setResponseValidator(responseValidator: ApiCallbackFunction | null): ApiSettings;
    /** @returns The response validator. */
    getResponseValidator(): ApiCallbackFunction;
}