composer/tests/Composer/Test/Plugin/Fixtures/plugin-v2/composer.json

{
    "name": "plugin-v2",
    "version": "2.0.0",
    "type": "composer-plugin",
    "autoload": { "psr-0": { "Installer": "" } },
    "extra": {
        "class": "Installer\\Plugin2"
    }
}