At least PHP 7.3 version is now required.
OneSignal\OneSignal client now requires always to provide OneSignal\Config.
OneSignal\OneSignal client now expects Psr\Http\Client\ClientInterface as a second arguments instead of Http\Client\Common\HttpMethodsClient and is mandatory.
OneSignal\OneSignal client now requires always to provide Psr\Http\Message\RequestFactoryInterface as a third argument and Psr\Http\Message\StreamFactoryInterface as a fourth argument.
Replaced magic __get method with __call in OneSignal\OneSignal, so from now calls like $oneSignal->apps must be used as $oneSignal->apps(). It is better to use Dependency injection, because these calls will construct new instances.
Removed OneSignal\Exception\OneSignalException and added OneSignal\Exception\OneSignalExceptionInterface.
Removed setConfig and setClient methods in OneSignal\OneSignal. You can build new instances with different configs or http clients.

Onesignal Php Api Laravel Package