@Entity
@Audited(withModifiedFlag = true)
public abstract class Element {
  @Id
  private Long id;
  private String name;

  @ElementCollection
  @CollectionTable(
      name = "element_tags",
      joinColumns = @JoinColumn(name = "element_id", referencedColumnName = "id"),
      foreignKey = @ForeignKey(name = "fk_element_tags_on_element_id"))
  private List<String> tags = new ArrayList<>();

  @ManyToMany
  @OrderBy("plannedEnd asc")
  @JoinTable(
      name = "element_milestones",
      joinColumns = @JoinColumn(name = "element_id", referencedColumnName = "id"),
      inverseJoinColumns =
      @JoinColumn(name = "milestone_id", referencedColumnName = "milestone_id"),
      foreignKey = @ForeignKey(name = "fk_element_milestones_on_element_id"),
      inverseForeignKey = @ForeignKey(name = "fk_element_milestones_on_milestone_id"))
  private Set<Milestone> milestones = new HashSet<>();
...
}