@Override
  public boolean verifyMember(ID mbr, String reason) {
    return mbr != null && memberExists(mbr)
        && services.getHealthMonitor()
            .checkIfAvailable(mbr, reason, false);
  }
in order to avoid split-brain occurring when a member is shutting down due to race conditions
in view management we add it as a shutdown member when we receive a shutdown message. This is
not the same as a SHUNNED member.
geode-membership/src/main/java/org/apache/geode/distributed/internal/membership/gms/GMSMembership.java