@Override
 public Paper merge(Paper entity) {
   if (entity.getId() != null) {
     return repo.save(entity);
   }
   return null;
 }
 @Override
 public List<Paper> findAll() {
   return repo.findAll();
 }
 @Override
 public void remove(Paper entity) {
   repo.delete(entity);
 }
 @Override
 public Paper persist(Paper entity) {
   return repo.save(entity);
 }
 @Override
 public Paper find(Long id) {
   return repo.findOne(id);
 }