public Set<InternalDistributedMember> getLocatorDistributionManagerIds() {
    return distribution.getMembersNotShuttingDown().stream()
        .filter((id) -> id.getVmKind() == LOCATOR_DM_TYPE).collect(
            Collectors.toSet());
  }
test method to get the member IDs of all locators in the distributed system
geode-core/src/main/java/org/apache/geode/distributed/internal/ClusterDistributionManager.java