implemente HasLen trait

[aimericsr]

I write an axum application and I'm using the validator crate to validate the JSON body. I would like to use Secrete<String> for password to not leak sensitive information when I log the request but validator require that the type implement HasLen. I could implement it myself but in Rust we can't implement trait on external struct.

I was wondering if this was a security reason or if it is possible to implement.