Doctrine ArrayCollection ->toArray() usage modifies original array in collection

ArrayCollectionTest.php

<?php

use Doctrine\Common\Collections\ArrayCollection;

class ArrayCollectionTest extends \PHPUnit_Framework_TestCase
{
    public function testModifiesOriginalCollection()
    {
        $data = array(
            1 => new Destination(),
            2 => new Destination(),
            3 => new Destination(),
        );
        $collection = new ArrayCollection($data);

        /** @var Destination $destination */
        foreach ($collection->toArray() as $key => $destination) {
            if (0 === ($key % 2)) {
                $destination->setEnabled(false);
            }
        }

        // Collection exposes its internal $this->_elements array, so changes to
        // ->toArray() values are reflected in the original Collection
        /** @var Destination $d */
        foreach ($collection as $k => $d) {
            $this->assertTrue($d->isEnabled(), sprintf("Destination %d is disabled when we expected it to be enabled", $k));
        }
    }
}

class Destination
{
    // Defaults true!
    private $enabled = true;

    public function setEnabled($bool) {
        $this->enabled = $bool;
    }

    public function isEnabled() {
        return $this->enabled;
    }
}