@Override
  void setMemoryThresholdFlag(MemoryEvent event) {
    if (event.getState().isCritical() && !event.getPreviousState().isCritical()
        && (event.getType() == ResourceType.HEAP_MEMORY
            || (event.getType() == ResourceType.OFFHEAP_MEMORY && getOffHeap()))) {
      // update proxy bucket, so that we can reject operations on those buckets.
      getRegionAdvisor().markBucketsOnMember(event.getMember(), true/* sick */);
    } else if (!event.getState().isCritical() && event.getPreviousState().isCritical()
        && (event.getType() == ResourceType.HEAP_MEMORY
            || (event.getType() == ResourceType.OFFHEAP_MEMORY && getOffHeap()))) {
      getRegionAdvisor().markBucketsOnMember(event.getMember(), false/* not sick */);
    }
  }
Changes the CustomExpiry for idleTimeout for values in the region

@param custom the new CustomExpiry
@return the old CustomExpiry
geode-core/src/main/java/org/apache/geode/internal/cache/PartitionedRegion.java