default void preSetUserQuota(final ObserverContext<MasterCoprocessorEnvironment> ctx,
    final String userName, final String namespace, final GlobalQuotaSettings quotas)
    throws IOException {
  }
Called before the quota for the user on the specified namespace is stored.
@param ctx       the environment to interact with the framework and master
@param userName  the name of user
@param namespace the name of the namespace
@param quotas    the current quota for the user on the namespace
hbase-server/src/main/java/org/apache/hadoop/hbase/coprocessor/MasterObserver.java