@Override
  public boolean isRolePresent(Role role) {
    Set<InternalDistributedMember> mbrs = getDistributionManagerIds();
    for (InternalDistributedMember mbr : mbrs) {
      Set<Role> roles = mbr.getRoles();
      for (Role mbrRole : roles) {
        if ((mbrRole).equals(role)) {
          return true;
        }
      }
    }
    return false;
  }
Returns true if at least one member is filling the specified role
geode-core/src/main/java/org/apache/geode/distributed/internal/ClusterDistributionManager.java