default void postListNamespaces(ObserverContext<MasterCoprocessorEnvironment> ctx,
    List<String> namespaces) throws IOException {
  }
Called after a listNamespaces request has been processed.
@param ctx        the environment to interact with the framework and master
@param namespaces the list of namespaces about to be returned
@throws IOException if something went wrong
hbase-server/src/main/java/org/apache/hadoop/hbase/coprocessor/MasterObserver.java