Handling reduntant columns with hibernate/jpa/spring data - postgresql

Question

i'm kinda struggling mapping the following schema with hibernate
table_a (A1_ID,A2_ID) --> PK = (A1_ID, A2_ID)
table_b (A1_ID, A2_ID, B1_ID) --> PK =(A1_ID, A2_ID, B1_ID)
where table_b's A1_ID and A2_ID should be foreingkey referencing respective table_A's columns
There is a one-to-many from TABLE_A to TABLE_B where TABLE_B's primary key is partially shared with TABLE_A's primary key
What I've tried so far
#Data
#Entity
#Table(name = "table_a")
#IdClass(TableA.TableAKey.class)
public class TableA {
#Id
#Column(name = "A1_ID)
private String a1_id;
#Id
#Column(name = "A2_ID)
private String a2_id;
#OneToMany(mappedBy = "tableA",fetch = FetchType.EAGER, cascade = CascadeType.ALL)
private List<TableB> tableB;
#Data
static class TableAKey implements Serializable {
private String a1_id;
private String a2_id
}
}
**CHILD ENTITY**
#Data
#Entity
#Table(name = "table_b")
#IdClass(TableB.TableBKey.class)
public class TableB {
#Id
#Column(name = "B1_ID)
private String b1_id;
#Id
#ManyToOne(cascade = CascadeType.ALL)
#JoinColumns({
#JoinColumn(name = "a1_id", insertable = false, updatable = false),
#JoinColumn(name = "a2_id", insertable = false, updatable = false)
)}
private TableA tableA;
#Column(name = "A1_ID)
private String a1_id;
#Column(name = "A2_ID)
private String a2_id;
#Data
static class TableAKey implements Serializable {
private String b1_id;
private TableA tableA;
}
}
I was expecting i could be able to do something like this:
TableA tableA = new TableA();
t.setA1_id("a1id");
t.setA2_id("a2id");
TableB tableB = new TableB();
tableB.setB1Id("b1Id");
tableA.setTableB(Arrays.asList(tableB));
tableARepository.save(tableA);
And the code above I was expecting to "magically" perform the following insert at DB
INSERT INTO table_A (A1_ID,A2_ID) VALUES ('a1id',a2id');
INSERT INTO table_B (A1_ID,A2_ID, B1_ID) VALUES ('a1id',a2id','b1id')
but instead i get a "the column index is out of range: n, number of columns n-1".
I also tried with some embeddedId approach, using referenceColumnName but nothing.
Am I doing something wrong in the mapping or in the object creation process?
The problem is a lot similar to the following
https://hibernate.atlassian.net/browse/HHH-14340