When TLS is enabled, this parameter specifies the name of the
file containing Radiator's certificate chain. The certificate chain is
sent to the TLS peer and validated by the peer during TLS setup. The
certificate chain must be in PEM format. This should be used alternatively
or additionally to TLS_CertificateFile
for explicitly
constructing the certificate chain, which is sent to the peer in addition
to the Radiator's own certificate.