I have 3 tables:
table 1 has primary key table1Id, has one to many relationship with table3
table 2 has primary key table2Id, has one to many ralationship with table 3
table 3 has composite primary key table3Id = (table1Id,table2Id)

My entities are as follows:

public class Table1 {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "table1Id")
private Integer table1Id;

@OneToMany(mappedBy = "table3Id.table1id", cascade = CascadeType.ALL)
private Set<Table3> t3 = new HashSet<Sample>();

---- etc. etc
}

public class Table2 {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "table2Id")
private Integer table2Id;

---- etc, etc
}

public class Table3 {

@EmbeddedId
private Table3PK table3Id;

--- etc, etc
}

@Embeddable
public class Table3PK implements Serializable {

private static final long serialVersionUID = -9059611979460128106L;

@NotNull
@ManyToOne
@JoinColumn(name = "table2Id", referencedColumnName = "table2Id")
private Table2 table2;

@NotNull
@ManyToOne(cascade = CascadeType.ALL)
@JoinColumn(name = "table1Id", referencedColumnName = "table1Id")
private Table1 table1;

----- etc. etc
}

When I try to commit an entity Table1, I get a null pointer exception because the table2Id is null. In other words, it is not inserting a new row in table2 correctly. I think my mappings are screwed up. Any ideas?
Thanx