from nx_secure_tls.h:1581
UINT _nx_secure_tls_session_certificate_callback_set(NX_SECURE_TLS_SESSION *tls_session,
ULONG (*func_ptr)(NX_SECURE_TLS_SESSION *session,
NX_SECURE_X509_CERT *certificate));
Implemented in nx_secure_tls_session_certificate_callback_set.c:83