question: @ Transactional public RoleDTO save ( RoleDTO dto ) { if ( dto == null ) { return null ; } Role role ; if ( dto . isIdSet ( ) ) { role = roleRepository . findOne ( dto . id ) ; } else { role = new Role ( ) ; } role . setRoleName ( dto . roleName ) ; return toDTO ( roleRepository . save ( role ) ) ; }
target:  Save the passed dto as a new entity or update the corresponding entity if any.