private void updateParentTimestampsFor(Iterable<? extends PropertyEntry<?>> propertyEntries, long currentTime) {
    if (propertyEntries == null) return;
    Set<PropertyContainer> updatedPropertyContainers = null;
    for (PropertyEntry<?> propertyEntry : propertyEntries) {
      if (updatedPropertyContainers == null)
        updatedPropertyContainers = new HashSet<PropertyContainer>();
      updatedPropertyContainers.add(propertyEntry.entity());
    }
    if (updatedPropertyContainers != null)
      updateTimestampsFor(updatedPropertyContainers, currentTime);
  }