Foreign key part of a multi-Primary key

My tables are the following :

CREATE TABLE table1
(
    id BIGSERIAL PRIMARY KEY NOT NULL,
    param1            varchar(255)
);

CREATE TABLE table2
(
    id_table1         BIGINT NOT NULL,
    pk2 varchar(255) NOT NULL,
    param2 varchar(255) NOT NULL,
    CONSTRAINT fk_table1 FOREIGN KEY (id_table1) REFERENCES merging_configuration(id)
);

ALTER TABLE merging_configuration_type
    ADD PRIMARY KEY (id_table1, pk2);

I really need the (id_table1, pk2) to be the key

So In hibernate I wrote the following classes:

@Entity(name = "table1")
public class Table1 {

  @Id
  private Long id;

  private String param1;

  @OneToMany
  @JoinColumn(name = "id_table1")
  private List<Table2> table2list;

  // constructors, getters, setters…
}

@Entity(name = "table2")
public class Table2 {

  @EmbeddedId
  private Table2Id id;

  private String param2;

}

@Embeddable
public class Table2Id implements Serializable {

  @Column(name = "id_table1")
  private Long idTable1;

  @Column(name = "pk2")
  private String pk2;

}

So everything compile and the get functions works perfectly but I cannot POST or PUT anything with the Table1Repository.save(entity):

• case 1: the keys in table2List of my entity are the same as for the database: the param1 updates but not param2
• case 2: table2List of my entity does not contains existing data in the database: I have this error in the logs:

[ERROR] o.h.e.j.s.SqlExceptionHelper - ERROR: a NULL value violates the NOT NULL constraint of the column "id_table1" in the relation "table2".
  Meaning: The failed row contains (null, myPK2, myParam2)

• case 3 : table2Listof my entity contains non existing data in the database: the .save throw an error with the following message : Unable to find path.Table2 with id Table2Id(idTableB=1, pk2=myPK2)

Could anyone help me ? I think there is a problem with my entities but I don't see anything else that could work

Thanks a lot