public ConfigChangeLockResult lockForConfigChange(long windowStart, long windowEnd) {
    if (this.registry == null) {
      throw new IllegalStateException("Not allowed to call lockForConfigChange before serviceInit");
    }
    if (isDynamic) {
      LlapZookeeperRegistryImpl zkRegisty = (LlapZookeeperRegistryImpl)registry;
      return zkRegisty.lockForConfigChange(windowStart, windowEnd);
    } else {
      throw new UnsupportedOperationException("Acquiring config lock is only allowed for dynamic registries");
    }
  }
Locks the Llap Cluster for configuration change for the given time window.
@param windowStart The beginning of the time window when no other configuration change is allowed.
@param windowEnd The end of the time window when no other configuration change is allowed.
@return The result of the change (success if the lock is succeeded, and the next possible
configuration change time
llap-client/src/java/org/apache/hadoop/hive/llap/registry/impl/LlapRegistryService.java