@UnstableApi
    static MultipartFile of(String name, String filename, File file, HttpHeaders headers) {
        requireNonNull(file, "file");
        return of(name, filename, file.toPath(), headers);
    }
Creates a new {@link MultipartFile}.
@param name the name parameter of the {@code "content-disposition"}
@param filename the filename parameter of the {@code "content-disposition"}
                header.
@param file the file that stores the {@link BodyPart#content()}.
@param headers HTTP part headers.
core/src/main/java/com/linecorp/armeria/common/multipart/MultipartFile.java