[Swagger] Added support for customizing the Definition key

[lyrixx]

Q	A
Bug fix?	no
New feature?	yes
BC breaks?	no
Deprecations?	no
Tests pass?	yes
Fixed tickets	#1583
License	MIT
Doc PR	api-platform/docs#368

---

Hello.

I want to customize the Definition key as state in #1583.

I found this way:

/**
 * @ApiResource(
 *      collectionOperations={
 *          "post"={
 *              "method"="POST",
 *              "denormalization_context"={"groups"={"v2_user_read"}, "swagger_definition_name": "HERE_WE_GO"},
 *          },
 *      },
 * )
 */
class User
{

And in order to reduce the code duplication,
when there are many (de)normalization_context,
we can use this shortcut:

/**
 * @ApiResource(
 *      collectionOperations={
 *          "post"={
 *              "method"="POST",
 *              "denormalization_context"=User::API_CREATION_WRITE,
 *          },
 *      },
 * )
 */
class User
{
    const API_CREATION_WRITE = [
        'groups' => ['v2_user_creation_write'],
        'swagger_definition_name' => 'CreationWrite',
    ];
}

---

If this RFC is accepted I will do the following:

• Make tests
• Removed the definition_name in the serializer execution
• Make a Documenation PR

[dunglas]

Thanks @lyrixx!