How to make JPA enforce the right FK constraint among many of them?

Question

I have 4 tables : TABLE_A, TABLE_B, TABLE_C, TABLE_RESULT

Constraints :

1. FK_TABLE_A_ID is a foreign key refrerences IDA primary key in TABLE_A
2. FK_TABLE_B_ID is a foreign key refrerences IDB primary key in TABLE_B
3. FK_TABLE_C_ID is a foreign key refrerences IDC primary key in TABLE_C
4. Only one foreign column is set at the same time

Table_A :

IDA	Field_A1	Field_AN
1	dataA11	dataA12
2	dataA21	dataA22
3	dataA32	dataA32

Table_B :

IDB	Field_B1	Field_BN
1	dataB11	dataB12
2	dataB21	dataB22
3	dataB32	dataB32

Table_C :

IDC	Field_C1	Field_CN
1	dataB11	dataB12
2	dataB21	dataB22
3	dataB32	dataB32

TABLE_RESULT:

ID	FK_TABLE_A_ID	FK_TABLE_B_ID	FK_TABLE_C_ID
1	1	NULL	NULL
2	NULL	2	NULL
3	NULL	NULL	3

Not allowed cases :

ID	FK_TABLE_A_ID	FK_TABLE_B_ID	FK_TABLE_C_ID
1	NULL	NULL	NULL
2	1	2	NULL
3	1	NULL	3
4	NULL	2	3
5	1	2	3

Some tables are in production environnement, and this design is imposed i don't have other options like refactoring the existing code or modifying the db schema.

1. I'm wondering how to map those relations in order to enforce the 4th constraint. Any suggestions and hints will be appreciated

2. Is it possible to make FK_TABLE_A_OR_B_OR_C_ID reference multiple columns on multiple tables and add a new TYPE column to know which table is referenced.

ID	FK_TABLE_A_OR_B_OR_C_ID	TYPE
1	1	A
2	2	B
3	3	C