Empty "scopes" bug

[GSokol]

If I make empty scopes in security scheme:

<?php

use Swagger\Annotations as SWG;

/**
 * @SWG\SecurityScheme(
 *     securityDefinition="oauth",
 *     type="oauth2",
 *     flow="password",
 *     tokenUrl="<SOME_URL>",
 *     scopes={}
 * )
 */

it produces invalid swagger.json:

{
// ...
    "securityDefinitions": {
        "oauth": {
            "type": "oauth2",
            "flow": "password",
            "tokenUrl": "http://dev.oauth.platoon.scnetservices.ru/oauth/v2/token",
            "scopes": {}
        }
    }
// ...
}