disk.kind() reports USB flash drive as DiskKind::HDD

[vExcess]

Describe the bug
I'm using Linux Mint and sysinfo v0.30.3. disk.kind() is reporting my USB flash drive as a HDD. I'd think it would report as DiskKind::SSD or DiskKind::Unknown because flash drives are more similiar to SSDs than they are to HDDs. Is this a bug or intentional?

To Reproduce

use sysinfo::{
    Disks, DiskKind
};

fn main() {
    let disks = Disks::new_with_refreshed_list();
    for disk in disks.list() {
        let kind = match disk.kind() {
            DiskKind::HDD => format!("{}", "HDD"),
            DiskKind::SSD => format!("{}", "SSD"),
            _ => format!("{}", "Unknown")
        };
        let name = match disk.name().to_str() {
            Some(res) => format!("{}", res),
            None => format!("{}", ""),
        };
        let file_system = match disk.file_system().to_str() {
            Some(res) => format!("{}", res),
            None => format!("{}", ""),
        };
        let total_space = format!("{}", disk.total_space());
        let available_space = format!("{}", disk.available_space());
        let mount_point = match disk.mount_point().to_str() {
            Some(path_str) => format!("{}", path_str),
            None => format!("{}", "ERR")
        };
        println!("{} {} {} {} {} {}", kind, name, file_system, total_space, available_space, mount_point);
    }
}

Output:

SSD /dev/sda3 ext4 982818799616 903877967872 /
SSD /dev/sda2 vfat 536834048 530464768 /boot/efi
HDD /dev/sdb1 exfat 62019076096 54214262784 /media/server/VINCENT USB

[GuillaumeGomez]

Would be nice to be able to recognize a flash drive indeed. I won't have much time in the coming weeks so don't hesitate to take a look!

[CarterLi]

That's because /sys/block/sdb/queue/rotational is 0

See https://unix.stackexchange.com/questions/439109/set-usb-flash-drive-as-non-rotational-drive