export interface IMultipartFormDataAppendOptions {
    filename: string;
    contentType?: string;
}
/**
 * Minimal multipart/form-data encoder for the values accepted by SmartRequest.
 */
export declare class MultipartFormData {
    private readonly boundary;
    private readonly parts;
    constructor(boundary?: string);
    append(name: string, value: string | Uint8Array, options?: IMultipartFormDataAppendOptions): void;
    resolveMissingContentTypes(resolver: (filename: string) => string | null): void;
    getHeaders(): Record<string, string>;
    getContentLength(): number;
    toArrayBuffer(): ArrayBuffer;
    getChunks(): Iterable<Uint8Array>;
    private getPartHeader;
    private validateContentType;
}