Condition $expression hint as string

[zajca]

In examples like https://github.com/lexik/LexikFormFilterBundle/blob/master/Resources/doc/working-with-the-bundle.md#ii-filter-customization user can see return $filterQuery->createCondition($expression, $parameters); where $expressing can be Composite but internally phpdoc hint is string. This will throw error in static analysis like Phpstan.
I suggests that this should be changed to mixed or in documentation should be $expression cast to string
return $filterQuery->createCondition((string)$expression, $parameters);

[FabienSalles]

Same problem here, I will disable the error on PHPStan but even my IDE complains.

Is there a reason to have a string type in this phpdoc ?