Function message_encode_text 

pub fn message_encode_text<M>(
    n: u32,
    f: &UnknownFields,
    enc: &mut TextEncoder<'_>,
) -> Result
where
    M: Message + TextFormat + Default,

Available on crate feature text and (crate features json or text) only.

Textproto encode for a message-typed extension: decode M from the unknown fields (merge semantics), write as a { ... } message body.