Allow recursive nesting of AdditionalProperties in Attributes

[rien-vroom-cquential]

Since nested AdditionalProperties have been allowed for a while through #706 also allow it through Attributes and not only with annotations.

[DerManoMann]

It would be great if you could add a simple example of the nesting in the tests/Fixtures/Scratch folder.

Something like this (still missing the nesting):

// NestedAdditionalProperties.php
<?php declare(strict_types=1);

/**
 * @license Apache 2.0
 */

namespace OpenApi\Tests\Fixtures\Scratch;

use OpenApi\Attributes as OAT;

#[OAT\Schema(
    additionalProperties: new OAT\AdditionalProperties(
        type: 'string',
        schema: new OAT\Schema(
            type: 'object',
        )
    )
)]
class NestedAdditionalPropertiesModel
{
}

#[OAT\Info(
    title: 'Nested Additional Properties',
    version: '1.0'
)]
#[OAT\Get(
    path: '/api/endpoint',
    description: 'An endpoint',
    responses: [new OAT\Response(response: 200, description: 'OK', ref: NestedAdditionalPropertiesEndpoint::class)]
)]
class NestedAdditionalPropertiesEndpoint
{
}

Running the scratch test will create the corresponding .yaml file which you should check for correctness.

[DerManoMann]

Just needs a code style fix then should be good to go.

Thanks.

[DerManoMann]

Thanks @rien-vroom-cquential