public EntityLock namespaceLock(String namespace, String description, Abortable abort) {
    LockRequest lockRequest = buildLockRequest(LockType.EXCLUSIVE, namespace, null, null,
      description, ng.getNonceGroup(), ng.newNonce());
    return new EntityLock(conf, stub, lockRequest, abort);
  }
LocCreate a new EntityLock object to acquire exclusive lock on a namespace. Clients can not
acquire shared locks on namespace.
hbase-server/src/main/java/org/apache/hadoop/hbase/client/locking/LockServiceClient.java