private void forceDisconnect(String reason) {
    isStopping = true;
    if (!isJoined) {
      joinResponse[0] =
          new JoinResponseMessage<>(
              "Stopping due to ForcedDisconnectException caused by '" + reason + "'", -1);
      isJoined = false;
      synchronized (joinResponse) {
        joinResponse.notifyAll();
      }
    } else {
      services.getManager().forceDisconnect(reason);
    }
  }
Transitions this member into the coordinator role. This must be invoked under a synch on
viewInstallationLock that was held at the time the decision was made to become coordinator so
that the decision is atomic with actually becoming coordinator.

@param oldCoordinator may be null
geode-membership/src/main/java/org/apache/geode/distributed/internal/membership/gms/membership/GMSJoinLeave.java