@Override
  public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + (regionEntry == null ? 0 : regionEntry.hashCode());
    result = prime * result + (region == null ? 0 : region.hashCode());
    return result;
  }
Used to create a cheap Region.Entry that can be passed to the CustomExpiry callback
geode-core/src/main/java/org/apache/geode/internal/cache/ExpiryRegionEntry.java