NamespaceDescriptor createNamespace(String namespace) throws Exception {
    if (namespace == null || namespace.trim().isEmpty())
      namespace = "ns" + counter.getAndIncrement();
    NamespaceDescriptor nd = NamespaceDescriptor.create(namespace).build();
    testUtil.getAdmin().createNamespace(nd);
    return nd;
  }
Waits {@code timeout} milliseconds for the HBase quota table to exist.
hbase-server/src/test/java/org/apache/hadoop/hbase/quotas/SpaceQuotaHelperForTests.java