Function group_headers_by_confidentiality 

fn group_headers_by_confidentiality(
    headers: Vec<(&'static str, HeaderType<'static>)>,
    from_addr: &str,
    timestamp: i64,
    is_encrypted: bool,
    is_securejoin_message: bool,
) -> HeadersByConfidentiality

Split headers based on header confidentiality policy. See HeadersByConfidentiality for more info.