void idleTimeoutChanged(ExpirationAttributes oldIdleTimeout) {
    // nothing
  }
Called if when we go from no listeners to at least one or from at least one to no listeners

@param nowHasListener true if we now have at least one listener; false if we now have no
       listeners
geode-core/src/main/java/org/apache/geode/internal/cache/AbstractRegion.java