In version 1.12.5p1 I can't have FTPS connection working anymore, because FTPS Dataconnection works only reusing the session of command connection.
It seems that calling currentSession() on the established command secure socket return always null, because SecureSocketImpl::onSessionCreated is never called even if session caching is enabled in Server Context using

enableSessionCache(true, "some id");
setSessionTimeout(timeout);
setSessionCacheSize(SSL_SESSION_CACHE_MAX_SIZE_DEFAULT);