Wildfly build with undertow and wildfly-core modules build from following sources:
https://github.com/stuartwdouglas/undertow/tree/sni
https://github.com/stuartwdouglas/wildfly-core/tree/sni
configure Undertow HTTPS listener with Elytron server-ssl-sni-context with two SNI mappings
www\\.example\\.com
.*\\.example\\.com
perform handshake with SNIHostName www.example.com
Client got peer certificate mapped by the more general mapping