default void postModifyNamespace(final ObserverContext<MasterCoprocessorEnvironment> ctx,
    NamespaceDescriptor oldNsDescriptor, NamespaceDescriptor currentNsDescriptor)
    throws IOException {
  }
Called after the modifyNamespace operation has been requested.
@param ctx                 the environment to interact with the framework and master
@param oldNsDescriptor     descriptor of namespace before modify operation happened
@param currentNsDescriptor current NamespaceDescriptor of the namespace
hbase-server/src/main/java/org/apache/hadoop/hbase/coprocessor/MasterObserver.java