protected Set<DistributedMember> getMembers(final String... memberIdNames) {
    ValidationUtils.returnValueThrowOnNull(memberIdNames,
        new GemfireRestException("No member found to run function"));
    final Set<DistributedMember> targetedMembers = new HashSet<>(ArrayUtils.length(memberIdNames));
    final List<String> memberIdNameList = Arrays.asList(memberIdNames);

    InternalCache cache = getCache();
    Set<DistributedMember> distMembers = cache.getDistributedSystem().getAllOtherMembers();

    // Add the local node to list
    distMembers.add(cache.getDistributedSystem().getDistributedMember());
    for (DistributedMember member : distMembers) {
      if (memberIdNameList.contains(member.getId())
          || memberIdNameList.contains(member.getName())) {
        targetedMembers.add(member);
      }
    }
    return targetedMembers;
  }
@return if the opValue is CAS then the existingValue; otherwise null
geode-web-api/src/main/java/org/apache/geode/rest/internal/web/controllers/AbstractBaseController.java