default void postSwitchRpcThrottle(final ObserverContext<MasterCoprocessorEnvironment> ctx,
    final boolean oldValue, final boolean newValue) throws IOException {
  }
Called after switching rpc throttle enabled state.
@param ctx      the coprocessor instance's environment
@param oldValue the previously rpc throttle value
@param newValue the newly rpc throttle value
hbase-server/src/main/java/org/apache/hadoop/hbase/coprocessor/MasterObserver.java