in grpc-gcp/src/main/java/com/google/cloud/grpc/GcpManagedChannel.java [1008:1020]
void processChannelStateChange(int channelId, ConnectivityState state) {
executeStateChangeCallbacks();
if (!fallbackEnabled) {
return;
}
if (state == ConnectivityState.READY || state == ConnectivityState.IDLE) {
// Ready
fallbackMap.remove(channelId);
return;
}
// Not ready
fallbackMap.putIfAbsent(channelId, new ConcurrentHashMap<>());
}