Spring JPA + Hibernate + Rest services + long time transactions

Question

I am using Spring JPA + Hibernate. I have a master for creation data, which call many REST services. They are located in one @ApiV1RestController, and their implementation is in one @Service. At different steps, I need to add data, process it, and commit at the end.

Example:

REST 1: /addItems Adding item

Item item = new Item();
item.setDescr("test");
itemRepository.flush();

REST 2: /addLocs Adding locations

Loc loc = new Loc();
loc.setDescr("test");
locRepository.flush();

REST 3: /checkItemLocs Executing a stored procedure where i work with data from previous REST-s

Step n. Commit

How to make the rest work in one transaction. Now the commit is automatically performed at the end of each rest service

I tried to use flush and @transactional