@Entity(name = "containing")
	public static class ContainingEntity {
		@Id
		private Integer id;

		@ManyToMany
		@JoinTable(inverseJoinColumns = @JoinColumn(name = "inverse"))
		@SortNatural
		private SortedSet<ContainedEntity> contained = new TreeSet<>();

		public Integer getId() {
			return id;
		}

		public void setId(Integer id) {
			this.id = id;
		}

		public SortedSet<ContainedEntity> getContained() {
			return contained;
		}

		public void setContained(SortedSet<ContainedEntity> contained) {
			this.contained = contained;
		}

	}


	@Entity(name = "contained")
	public static class ContainedEntity implements Comparable<ContainedEntity> {

		@Id
		private Integer id;

		@ManyToMany(mappedBy = "contained")
		private List<ContainingEntity> containing = new ArrayList<>();

		@Override
		public int compareTo(ContainedEntity o) {
			return getId() - o.getId();
		}

		public Integer getId() {
			return id;
		}

		public void setId(Integer id) {
			this.id = id;
		}

		public List<ContainingEntity> getContaining() {
			return containing;
		}

	}