public Map<String, SpaceQuotaSnapshot> getNamespaceQuotaSnapshots() {
    return readOnlyNamespaceSnapshots;
  }
Returns an unmodifiable view over the current {@link SpaceQuotaSnapshot} objects for each HBase
namespace with a quota defined.
hbase-server/src/main/java/org/apache/hadoop/hbase/quotas/QuotaObserverChore.java