@Override
  public boolean isReconnecting() {
    InternalDistributedSystem rds = reconnectDS;
    if (!attemptingToReconnect) {
      return false;
    }
    if (reconnectCancelled) {
      return false;
    }
    return (rds == null || !rds.isConnected());
  }
Returns true if we are reconnecting the distributed system or reconnect has completed. If this
returns true it means that this instance of the DS is now disconnected and unusable.
geode-core/src/main/java/org/apache/geode/distributed/internal/InternalDistributedSystem.java