composer/tests/Composer/Test/Plugin/Fixtures/plugin-v4/Installer/Plugin1.php

<?php

namespace Installer;

use Composer\Composer;
use Composer\Plugin\PluginInterface;

class Plugin1 implements PluginInterface
{
    public $name = 'plugin1';
    public $version = 'installer-v4';

    public function activate()
    {
    }
}