@ModelAttribute

An object assigned with @ModelAttribute tag is automatically saved into Model. For Example:

@PostMapping("/add")
public String addItem(@ModelAttibute("item") Item item, Model model){
  itemRepository.save(item);
  //model.addAttribute("item",item); 
  // ^^this is automatically added so no need to write this
  return "items/item"
}

Really good ref

https://dahliachoi.tistory.com/44