Cannot resolve symbol 'QueryWrapper' or new QueryWrapper<>() cannot be clicked 【Solved】

Cannot resolve symbol 'QueryWrapper' if you find 

 First, check to see if the dependency package of mybatis-plus in your pm package has been imported.

(I am a father-son project here, and the parent project manages the version uniformly, so I didn’t write the version number. Generally, I have to write the version number, otherwise I can’t find it! )