Finalized two exceptions and MemoryCache.

Author: Bilge

src/Cache/InvalidCacheKeyException.php

@@ -3,7 +3,7 @@
 
 namespace ScriptFUSION\Porter\Cache;
 
-class InvalidCacheKeyException extends \RuntimeException implements \Psr\Cache\InvalidArgumentException
+final class InvalidCacheKeyException extends \RuntimeException implements \Psr\Cache\InvalidArgumentException
 {
     // Intentionally empty.
 }

src/Cache/MemoryCache.php

@@ -9,7 +9,7 @@
 /**
  * Provides an in-memory cache with a PSR-6 interface.
  */
-class MemoryCache extends \ArrayObject implements CacheItemPoolInterface
+final class MemoryCache extends \ArrayObject implements CacheItemPoolInterface
 {
     /**
      * @param string $key

src/Provider/ObjectNotCreatedException.php

@@ -6,7 +6,7 @@
 /**
  * The exception that is thrown when an object could not be created.
  */
-class ObjectNotCreatedException extends \RuntimeException
+final class ObjectNotCreatedException extends \RuntimeException
 {
     // Intentionally empty.
 }