Return Symfony ClockInterface in ClockSensitiveTrait

I don't understand why the ClockSensitiveTrait::mockTime returns a PSR ClockInterface, instead of a Symfony ClockInterface.

Is this done on purpose? Or was this a mistake?

Author: ruudk

src/Symfony/Component/Clock/Test/ClockSensitiveTrait.php

@@ -11,7 +11,7 @@
 
 namespace Symfony\Component\Clock\Test;
 
-use Psr\Clock\ClockInterface;
+use Symfony\Component\Clock\ClockInterface;
 use Symfony\Component\Clock\Clock;
 use Symfony\Component\Clock\MockClock;