// Gateway Interface
interface UserGateway {
    public function getUserData($userId);
}

// Gateway Class for External System 1
class ExternalSystem1Gateway implements UserGateway {
    public function getUserData($userId) {
        // Code to fetch user data from External System 1
        // For simplicity, we return a hardcoded response
        return [
            'id' => $userId,
            'name' => 'John Doe',
            'email' => 'john@example.com'
        ];
    }
}

// Gateway Class for External System 2
class ExternalSystem2Gateway implements UserGateway {
    public function getUserData($userId) {
        // Code to fetch user data from External System 2
        // For simplicity, we return a hardcoded response
        return [
            'userId' => $userId,
            'userName' => 'Jane Doe',
            'userEmail' => 'jane@example.com'
        ];
    }
}