@Nullable
    @VisibleForTesting
    Path multipartUploadsLocation() {
        return multipartUploadsLocation;
    }
Sets the {@link Path} for storing the files uploaded from
{@code multipart/form-data} requests.

@param multipartUploadsLocation the path of the directory which stores the files.
core/src/main/java/com/linecorp/armeria/server/VirtualHostBuilder.java