Function construct_proxy_request_parts 

pub(super) fn construct_proxy_request_parts(
    request_parts: Parts,
    config: &ServerConfiguration,
    socket_data: &SocketData,
    proxy_request_url: &Uri,
    headers_to_add: &[(HeaderName, String)],
    headers_to_replace: &[(HeaderName, String)],
    headers_to_remove: &[HeaderName],
    rewrite_host: bool,
) -> Result<Parts, Box<dyn Error + Send + Sync>>

Constructs a proxy request based on the original request.