http_type/upgrade_type/
enum.rs

1/// Represents different upgrade types.
2#[derive(Debug, Clone, PartialEq, Eq)]
3pub enum UpgradeType {
4    /// WebSocket protocol upgrade
5    WebSocket,
6    /// HTTP/2 cleartext upgrade (h2c)
7    H2c,
8    /// TLS upgrade (rare, experimental)
9    Tls(String),
10    /// Other custom or unknown upgrade protocols
11    Unknown(String),
12}