@Entity()
@Table()
public class Supplier implements Serializable {

        /** Contains the keys for the supplier, lets say sup_col1, sup_col2. */
 	@EmbeddedId()
	public SupplierPrimaryKey pk;
        
	@Column()
	public String someotherstuff, morestuff;

         /** I want to join the pk fields from this entity onto the pk fields
             of the account entity. */
        @OneToOne(targetEntity=Account.class)
	@JoinTable(joinColumns = { 
        @JoinColumn(name = "pk.account_col1", referencedColumnName = "pk.sup_col1"), 
        @JoinColumn(name = "pk.account_col2", referencedColumnName = "pk.sup_col2") })
	public Account account;

Exception Description: The @JoinColumns on the annotated element [field Account] from the entity class [class packages.Supplier] is incomplete. When the source entity class uses a composite primary key, a @JoinColumn must be specified for each join column using the @JoinColumns. Both the name and the referencedColumnName elements must be specified in each such @JoinColumn

 
SELECT t FROM Supplier s 
JOIN t.account a 
WHERE s.pk.accountNumber = 1 
AND (s.stat = '20' OR s.stat= '90') 
AND a.pk.division='Something' 

SELECT s, a FROM Supplier s
JOIN s.account a 
WHERE s.pk.accountNumber = 1 
AND (s.stat = '20' OR s.stat= '90') 
AND a.pk.division='Something'