magento2: Queue consumer handler can't be virtual type

⬆️ Looks like the issue is not resolved, is being reproduced, and still requires an attention

It’s still possible to reproduce this issue on Magento 2.4.0 Enterprise

How to reproduce

1. Create some service class like this

namespace Vendor\Module\Model;

class Consumer implements CustomConsumerInterface
{
    private CustomValidatorInterface $validator;

    public function __construct(
        CustomValidatorInterface $validator
    ) {
        $this->validator = $validator;
    }

    public function consume(SomeCustomInterface $foo): void
    {
        $this->validator->validate($foo);
    }
}

1. Create virtual type based on created class

<virtualType name="Vendor\Module\Model\VirtualConsumer" type="Vendor\Module\Model\Consumer">
        <arguments>
            <argument name="validator" xsi:type="object">Vendor\Module\Model\ConcreteValidator</argument>
        </arguments>
</virtualType>

1. Use virtual consumer in queue_consumer.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework-message-queue:etc/consumer.xsd">
    <consumer name="testConsumer"
              queue="test.queu"
              connection="amqp"
              maxMessages="1"
              handler="Vendor\Module\Model\VirtualConsumer::consume" />
</config>

1. Make sure setup:di:compile finished successfully
2. Run bin/magento queue:consumers:start testConsumer and see the error

In Handlers.php line 74:
                                                                                                                                                                              
  Service method specified as handler for of consumer "testConsumer" is not available. Given "Vendor\Module\Model\VirtualConsumer::consume"

This happens because it tries to create ClassReflection for virtual type in vendor/magento/framework/Reflection/MethodsMap.php:137 And I see that code which is responsible for that is still exists in the latest magento 2.4-develop branch - https://github.com/magento/magento2/blob/2.4-develop/lib/internal/Magento/Framework/MessageQueue/Consumer/Config/Validator/Handlers.php#L72

@engcom-Hotel I didn’t have time recently to check it again. I was waiting for your response for over one year, so I don’t think this should be closed just like this. I am going to examine that in two next week, so you can reopen this one.