Symfony version(s) affected: 5.1.6, 5.1.7

Description
Hello!

In one of our projects we have a class similar to this:

final class ExampleDTO
{
    private ?string $example;

    public function __construct(?string $example)
    {
        $this->example = $example;
    }

    public function getExample(): string
    {
        return $this->example ?? 'fallback';
    }
}

It's used in the context of api platform, where incoming data is being deserialized to this object.

Before with Symfony 5.1.5 the example property was detected as type ?string, after upgrading to 5.1.6/5.1.7 it's only detected as type string. Now when the incoming data contains a null value, it will fail with The type of the "example" attribute must be "string", "NULL" given.

I did some tests and was able to track this new behaviour down to the property-info component. I suspect this change to be the reason:
#38041

It looks like now the return type of getExample() is used instead of the property type hint (?string).

So I would like to ask if this is the expected behaviour and if yes, how can I make the old way work again (somehow influence the priorities?). Thanks in advance!

How to reproduce
I created a reproducer here:
https://github.com/rogamoore/property-info-bug

Steps:

• Checkout https://github.com/rogamoore/property-info-bug/releases/tag/old-behaviour (property-info 5.1.5)
• Run composer install
• Run symfony server:start
• Go to http://127.0.0.1:8000/
• Result:

^ array:1 [▼
  0 => Symfony\Component\PropertyInfo\Type {#116 ▼
    -builtinType: "string"
    -nullable: true
    -class: null
    -collection: false
    -collectionKeyType: null
    -collectionValueType: null
  }
]

• Checkout https://github.com/rogamoore/property-info-bug/releases/tag/new-behaviour (property-info 5.1.6)
• Run composer install
• Run symfony server:start
• Go to http://127.0.0.1:8000/
• Result:

^ array:1 [▼
  0 => Symfony\Component\PropertyInfo\Type {#116 ▼
    -builtinType: "string"
    -nullable: false
    -class: null
    -collection: false
    -collectionKeyType: null
    -collectionValueType: null
  }
]

Additional context
PHP 7.4.10