Gets the name of the application-layer protocol negotiated during
the handshake.
If the peer did not use the ALPN extension, or did not advertise a
protocol that matched one of conn's protocols, or the TLS backend
does not support ALPN, then this will be NULL. See
TlsConnection.setAdvertisedProtocols.
Gets the name of the application-layer protocol negotiated during the handshake.
If the peer did not use the ALPN extension, or did not advertise a protocol that matched one of conn's protocols, or the TLS backend does not support ALPN, then this will be NULL. See TlsConnection.setAdvertisedProtocols.