Hazelcast pings fail about mirrord HOT 2 OPEN

Hazelcast uses isReachable which goes to this code:
https://github.com/openjdk/jdk/blob/87bb66cea1b6b70fc4929e7a6e3788883f87e02d/src/java.base/unix/native/libnet/Inet4AddressImpl.c#L343

from mirrord.

I think a temporary, patchy solution would be to emulate that connection to port 7 is always successful. If you look at the above example, tcp_ping4 just calls connect((host, 7)) and if it succeeds it closes and it is reachable from it's perspective.
We should add

{
"feature": {"experimental": {"tcp_ping4_mock": true}}
}

that will trigger that magic behavior for now.

from mirrord.