PostMapping Logic errors

I have a method in my service that can save a fruit in all the stores that I have. It works well in main method, but not with Postman. When I test with Postman it creates just one instance of the fruit.

Service code

@Override
public Fruit addFruit(Fruit f) {
   Iterable<Store> stores=storeService.getAllStores();
   for (Store store : stores) {
	 Fruit fruit = new Fruit();
	 fruit.setStore(store);
	 fruit.setAlert(f.getAlert());
	 fruit.setCategory(f.getCategory());
	 fruit.setDesignation(f.getDesignation());
	 fruit.setLign(f.getLign());
	 fruit.setReference(f.getReference());
	 fruit.setStock(f.getStock());
	 f.setStore(store);
	 fruitRepository.save(fruit);
     }
 
  return f;    
}

*postman Json *

{
"reference":"reference1",
"category":"Citrus",
"designation":"Orange and Lemon",
"lign":20,
"stock":60
}

getAllstore services

 @Override
 public Iterable<Store> getAllStores() {
 return storeRepository.findAll();
 }

Controller

@Path("/fruits")
@POST
@Consumes(MediaType.APPLICATION_JSON_VALUE)
@Produces(MediaType.APPLICATION_JSON_VALUE)
public Fruit addProduit(@RequestBody Fruit f) {
	return fruitService.addFruit(f);
}

You need to return a collection of Fruit instead of one Fruit in the Controller and also in the Service, so you can return back what you have created in the database, and you can also check the result in Postman.

Service:

@Override 
public Set<Fruit> addFruit(Fruit f) {
  Iterable<Store> stores=storeService.getAllStores();
  Set<Fruit> createdFruits = new HashSet<>(  stores.size() )
  for (Store store : stores) { 
    Fruit fruit = new Fruit();
    fruit.setStore(store);
    fruit.setAlert(f.getAlert());
    fruit.setCategory(f.getCategory());
    fruit.setDesignation(f.getDesignation());
    fruit.setLign(f.getLign());
    fruit.setReference(f.getReference());
    fruit.setStock(f.getStock());
 //f.setStore(store);  // You don't need this 
    createdFruits.add( fruitRepository.save(fruit) ); 
  } 

  return createdFruits; 
}

Controller:

@Path("/fruits") 
@POST @Consumes(MediaType.APPLICATION_JSON_VALUE) @Produces(MediaType.APPLICATION_JSON_VALUE)
 public Set<Fruit> addProduit(@RequestBody Fruit f) {
   return fruitService.addFruit(f);
}