FleetHealthMonitor now requires a failTarget BiConsumer<String,String>
collaborator (no defaulting overload) and calls it exactly once when a
member transitions into GONE or NEVER_READY, via CB-568's idempotent
target-wide abandon() operation. The reason string names the real
terminal state. failTarget invocation retries up to
MAX_FAIL_TARGET_ATTEMPTS (3) within the same transition if it throws,
and never refires on a later tick where the state is unchanged.
Bridged.java wires messages::abandon as the production failTarget.
Dai Ha
0af902ec43