Type mismatch: cannot convert from T to S

There is a class:
```java
public class Common<T> {
    public <S extends T> S findOne(Object params) {
        return select(params)
    }

    private <S extends T> S selectOne(Object params) {
        return getSqlSession().selectOne(params);
    }
}
```
Using version 1.44.0, there were no errors. After upgrading to version 1.45.0, it prompts "Type mismatch: cannot convert from T to S"
