@Entity
public class DataPoint1 {
	@Id
	@GeneratedValue
	public long id;
	
	@ManyToMany
	@JoinTable(name = "REL_FOO_BAR", indexes = @Index(name = "FOO_BAR_IDX", columnList = "FOO_FK, BAR_FK"),
		joinColumns = @JoinColumn(name = "FOO_FK"), inverseJoinColumns = @JoinColumn(name = "BAR_FK"))
	public Set<DataPoint2> dataPoint2s;
}

@Entity
public class DataPoint2 {
	@Id
	@GeneratedValue
	public long id;
	
	@ManyToMany( mappedBy="dataPoint2s" )
	public Set<DataPoint1> dataPoint1s;
}