Amp/Future Type mismatch due to humbug/box namespace prefix

Hello,

I tried creating a custom TaskHandlerMiddleware and use it together with the grumphp-shim packages.
But because TaskHandlerMiddlewareInterface return signature defines Amp\Future and this namespace is not excluded from humbug/box namespace prefixing I'm experiencing the following error:

Fatal error: Declaration of -\CodeQuality\GrumPHP\Runner\TaskHandler\Middleware\ConfigureDefaultIgnores::handle(GrumPHP\Task\TaskInterface $task, GrumPHP\Runner\TaskRunnerContext $runnerContext, GrumPHP\Runner\StopOnFailure $stopOnFailure, callable $next): Amp\Future must be compatible with GrumPHP\Runner\TaskHandler\Middleware\TaskHandlerMiddlewareInterface::handle(GrumPHP\Task\TaskInterface $task, GrumPHP\Runner\TaskRunnerContext $runnerContext, GrumPHP\Runner\StopOnFailure $stopOnFailure, callable $next): _HumbugBox6e20aa8b1e92\Amp\Future in /Users/-/Projects/-/vendor/-/code-quality/src/GrumPHP/Runner/TaskHandler/Middleware/ConfigureDefaultIgnores.php on line 28

Should the Amp\Future namespace be excluded in the box.json or am I doing something wrong? :)

Start with box.json and the TaskHandlerMiddlewareInterface and ConfigureDefaultIgnores.php signatures named in the error. Reproduce the failure while installing the grumphp-shim packages and inspect how namespace prefixing affects Amp\Future. Done means the custom middleware and packaged interface have compatible return types without the reported fatal error.