This parameter specifies an upstream generalist DeleGate (MASTER-DeleGate)
to which this DeleGate will forward requests.
Forwarding to a MASTER-DeleGate can be filtered
by postfixing ":dstHostList";
only request toward destination servers listed in dstHostList are
forwarded to the MASTER-DeleGate.
When multiple MASTERs are given, they are tried in order until connection
to a MASTER succeed.
Optional "/masterControl" can be:
cache -- use the MASTER only if cache hits in the MASTER
teleport -- make a persistent Teleport connection to the MASTER