/**
 * Converts a plain object to a FormData instance.
 *
 * - If the value is an array:
 *   - An empty array appends a null.
 *   - Otherwise the array is split into Files and non-Files.
 *     - Each File is appended separately under the same key.
 *     - Non-File values are appended as a JSON string.
 * - An object (excluding File) is appended as a JSON string.
 * - Otherwise the value is appended as-is.
 *
 * @param data - The object containing key-value pairs to be converted.
 * @returns A FormData instance populated with the processed data.
 */
export declare const convertToFormData: <T extends object>(data: T) => FormData;