在撸SpringBoot2.0+的时候，JpaRepository中的findOne()传id报错

Inferred type 'S' for type parameter 'S' is not within its bound; 

SpringBoot 1.+的版本JpaRepository为

@NoRepositoryBean
public interface CrudRepository<T, ID extends Serializable> extends Repository<T, ID> {
    <S extends T> S save(S var1);

    <S extends T> Iterable<S> save(Iterable<S> var1);

    T findOne(ID var1);

    boolean exists(ID var1);

    Iterable<T> findAll();

    Iterable<T> findAll(Iterable<ID> var1);

    long count();

    void delete(ID var1);

    void delete(T var1);

    void delete(Iterable<? extends T> var1);

    void deleteAll();
}

SpringBoot2+版本的JpaRepository为

@NoRepositoryBean
public interface JpaRepository<T, ID> extends PagingAndSortingRepository<T, ID>, QueryByExampleExecutor<T> {
    List<T> findAll();

    List<T> findAll(Sort var1);

    List<T> findAllById(Iterable<ID> var1);

    <S extends T> List<S> saveAll(Iterable<S> var1);

    void flush();

    <S extends T> S saveAndFlush(S var1);

    void deleteInBatch(Iterable<T> var1);

    void deleteAllInBatch();

    T getOne(ID var1);

    <S extends T> List<S> findAll(Example<S> var1);

    <S extends T> List<S> findAll(Example<S> var1, Sort var2);
}

新版本获取findOne()方法可用类似方法解决

  @Test
   public void findOneTest(){
        Product product = new Product();
        product.setCategoryId(1);
        Example<Product> example = Example.of(product);
        Optional<Product> productOptional = respository.findOne(example);

        if (productOptional.isPresent()) {
            Product productResult =   productOptional.get();
            System.out.println(productResult.toString());
        } else {
            // handle not found, return null or throw
            System.out.println("no exit!");
        }

    }