1. The `PDO\Connection` and `PDO\Statement` classes have been made final.
2. The `PDOSqlsrv\Connection` and `PDOSqlsrv\Statement` classes have been made final and no longer extend the corresponding PDO classes.
## BC BREAK: Changes in driver-level exception handling
1. The `convertException()` method has been removed from the `Driver` interface. The logic of exception conversion has been moved to the `ExceptionConverter` interface. The drivers now must implement the `getExceptionConverter()` method.