TCPGOSSIP: discovery fails when physical address is not yet known by coordinator

In TCPGOSSIP, the GossipRouter stores logical address (UUID), logical name (e.g. "A") and physical address (e.g. 192.168.1.5:7800) of each member. When a member P runs the discovery in TCPGOSSIP, it fetches all of this information, so it can send messages to all members in its cluster.

However, when member Q, who hasn't yet run a discovery (e.g. as part of MERGE2), needs to send a message back to P, since P's physical address won't be known yet, this will fail.

A concrete uses case is this:

• A has joined the cluster, became the coordinator as only member and registered with the GossipRouter
• B runs the discovery protocol, fetches information about A from GossipRouter in a first phase
• In a second phase, B sends a GET_MBRS_REQ to A, this works as B knows A's physical address
• A receives B's request and wants to send a GET_MBRS_RSP back to B
• However, as A didn't include its own physical address, A won't be able to send a message back to B ! Therefore B doesn't join the cluster, and will only later be merged with A !
• Only after the periodic merge kicks in, which runs a discovery on A, will A get B's physical address and will be able to talk to B !

==> SOLUTION: simple, B sends it metadata (physical address, logical name) with the GET_MBRS_REQ to A, so A will have B's physical address to send a message back to B. This is actually done in the other discovery protocols as well, e.g. TCPPING or PING...