public void setCustomEntryIdleTimeout(CustomExpiry<K, V> custom) {
    regionAttributes.customEntryIdleTimeout = custom;
    regionAttributes.setHasCustomEntryIdleTimeout(true);
  }
Sets the idleTimeout CustomExpiry for the next {@code RegionAttributes} created.

@param custom the CustomExpiry to use; null means none will be used.
geode-core/src/main/java/org/apache/geode/cache/AttributesFactory.java