Remove getIterator method

Author: Steveb-p

lib/Doctrine/ODM/MongoDB/Iterator/CachingIterator.php

@@ -124,27 +124,18 @@ private function exhaustIterator() : void
         $this->iterator = null;
     }
 
-    private function getIterator() : Generator
-    {
-        if ($this->iterator === null) {
-            throw new RuntimeException('Iterator has already been destroyed');
-        }
-
-        return $this->iterator;
-    }
-
     /**
      * Stores the current item in the cache.
      */
     private function storeCurrentItem() : void
     {
-        $key = $this->getIterator()->key();
+        $key = $this->iterator->key();
 
         if ($key === null) {
             return;
         }
 
-        $this->items[$key] = $this->getIterator()->current();
+        $this->items[$key] = $this->iterator->current();
     }
 
     private function wrapTraversable(Traversable $traversable) : Generator