pub fn with_violation(field: impl Into<String>, description: impl Into<String>) -> Self {
        BadRequest {
            field_violations: vec![FieldViolation {
                field: field.into(),
                description: description.into(),
            }],
        }
    }
Creates a new [`BadRequest`] struct with a single [`FieldViolation`] in
`field_violations`.
tonic-types/src/richer_error/std_messages/bad_request.rs