minor #32786 add parameter type declarations to private methods (xabbuh)
minor #32786 add parameter type declarations to private methods (xabbuh)

This PR was merged into the 4.4 branch.

Discussion
----------

add parameter type declarations to private methods

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

Commits
-------

1b2aaa4a06 add parameter type declarations to private methods

symfony/Filesystem