public List/* <ControllerProfile> */ fetchControllers() {
    List/* <ControllerProfile> */ result = cachedControllerProfiles;
    if (result == null) {
      synchronized (cacheLock) {
        result = cachedControllerProfiles;
        if (result == null) {
          result = fetchProfiles(CONTROLLER_FILTER);
          cachedControllerProfiles = result;
        }
      }
    }
    return result;
  }
Returns an unmodifiable {@code List} of the {@code ControllerProfile}s for all known cnx
controllers.
geode-core/src/main/java/org/apache/geode/internal/cache/GridAdvisor.java