@Override
  void initialCriticalMembers(boolean localMemoryIsCritical,
      Set<InternalDistributedMember> criticalMembers) {
    for (InternalDistributedMember idm : criticalMembers) {
      getRegionAdvisor().markBucketsOnMember(idm, true/* 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