Fix "Document HydratorFactory does not support nullable date field" #2753

[frenchcomp]

Update code generated by the HydratorFactory for date to support nullable datetime field.

Q	A
Type	bug
BC Break	no
Fixed issues	#2753

Summary

These PR update only the HydratorFactory class to update the if condition to support nullable field like for other type.
It will update also the clone $return value, because $return can be 'null' and we can not clone null value in PHP.

[GromNaN]

Hello @frenchcomp, thanks for contributing this fix.
Apparently it's breaking an existing test case. Also, the feature needs to be covered by a new non-regression test.

1) Doctrine\ODM\MongoDB\Tests\Functional\DateTest::testDateInstanceValueChangeDoesCauseUpdateIfValueIsTheSame
Failed asserting that an array is not empty.

/home/runner/work/mongodb-odm/mongodb-odm/tests/Doctrine/ODM/MongoDB/Tests/Functional/DateTest.php:102

[GromNaN]

We avoid usage of empty as it covers too many cases. Maybe we can refactor the condition like this;

Suggested change

	if (isset($data['%1$s']) || (! empty($this->class->fieldMappings['%2$s']['nullable']) && array_key_exists('%1$s', $data))) {
	if (array_key_exists('%1$s', $data) && ($data['%1$s'] !== null || $this->class->fieldMappings['%2$s']['nullable'] ?? false)) {

[frenchcomp]

Yes, I understand, I had just copied another part of the factory. In an external project I try to maintain consistency.
I forgeted the flag WIP. I just wanted to run the tests, not being able to do it on my machine

[GromNaN]

Indeed, I wasn't aware that empty is used a lot in this class.