Function encode_injector_declaration 

pub fn encode_injector_declaration(
    client_id: &str,
    ticket: Option<&str>,
) -> Vec<u8> 

Build the IPC_DECLARE_INJECTOR_PREFIX control frame a writer sends to declare itself an autonomous injector. The inverse of parse_injector_declaration, kept beside it so a producer’s declaration and the router’s parse cannot drift on the wire format. ticket is the pairing-key attestation for client_id; omit it on an unpaired node.