[HttpFoundation] Revert getClientIp @return docblock

[ossinkine]

Q	A
Branch?	3.4
Bug fix?	yes
New feature?	no
BC breaks?	no
Deprecations?	no
Tests pass?	yes
License	MIT

This PR reverts #22418, see the comment #22418 (comment)

[nicolas-grekas]

I just tried running this and it returned null, with no "undefined" notice:

$r = new Request();

var_dump($r->getClientIp());

[ossinkine]

I think the docblock contains a type that must be, but not one that can be.
There is a lot of not null fields in Request class which will be null after new Request().

[ostrolucky]

No, docblock must specify type it returns

[ossinkine]

But now it is not so, we must be consistent. If we want the docblock to contain what the method returns, we need to add |null to other fields and check that the field is not null when we call the getter, but we don’t do that, it is a huge number of redundant checks.

[fabpot]

Thank you @ossinkine.