failed to insert 1-to-many entities using Spring Data JPA

may related to this, i have to insert header and 2 lines individually to walk around.

spring-boot-starter-data-jpa:2.6.3

select first 1 header_

select header_

insert into header_

insert into line_

select dbinfo('serial8') from informix.systables where tabid=1

insert into line_

select dbinfo('serial8') from informix.systables where tabid=1

A different object with the same identifier value was already associated with the session :

 nested exception is javax.persistence.EntityExistsException:

A different object with the same identifier value was already associated with the session