default void onConfigurationChange(Configuration config) {
    // noop
  }
Allows for BlockCache implementations to provide a mean to refresh their configurations. Since
HBASE-29249, CacheConfig implements PropagatingConfigurationObserver and registers itself
together with the used BlockCache implementation for notifications of dynamic configuration
changes. The default is a noop.
@param config the new configuration to be updated.
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/BlockCache.java