以字节为单位获取Total TAR内容大小

Question

有没有办法发现tar.gz中所有文件的总未压缩大小而不迭代TarArchiveInputStream中的所有TarArchiveEntries，如下所示？

TarArchiveInputStream tin = new TarArchiveInputStream(new GZIPInputStream(new FileInputStream("/path/to/my.tar.gz")));
TarArchiveEntry ten;
long size = 0;
while( (ten = tin.getNextTarEntry()) != null) {
    size += ten.getSize();
}