message: add test for auth key from str func not panic
  Closes:
diff: @@ -300,3 +300,14 @@ impl fmt::Display for AuthenticationKey {
  write!(f, "{:#x}", self)
  }
  }
  +
  +#[cfg(test)]
  +mod tests {
  + use crate::transaction::authenticator::AuthenticationKey;
  + use std::str::FromStr;
  +
  + #[test]
  + fn test_from_str_should_not_panic_by_given_empty_string() {
  + assert!(AuthenticationKey::from_str("").is_err());
  + }
  +}
  