Spring data报错：Inferred type 'S' for type parameter 'S' is not within its bound;

Spring data报错：Inferred type ‘S’ for type parameter ‘S’ is not within its bound;

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参照 org.springframework.data.repository.query.QueryByExampleExecutor 源码：

findOne:

/**
 * Returns a single entity matching the given {@link Example} or {@literal null} if none was found.
 *
 * @param example must not be {@literal null}.
 * @return a single entity matching the given {@link Example} or {@link Optional#empty()} if none was found.
 * @throws org.springframework.dao.IncorrectResultSizeDataAccessException if the Example yields more than one result.
 */
 Optional findOne(Example example);

参照 org.springframework.data.repository.CrudRepository 源码：
findById:

/**
 * Retrieves an entity by its id.
 * 
 * @param id must not be {@literal null}.
 * @return the entity with the given id or {@literal Optional#empty()} if none found
 * @throws IllegalArgumentException if {@code id} is {@literal null}.
 */
Optional findById(ID id);

findOne(id) 用 findById(id).orElse(null) 替换即可。