title: MappingEntityClassesException - Mapping definition neither have entities nor collection
body: <p>I have written a product import which imports some product data via CLI command.
  When i run it multiple times the defined product property (<code>color</code>) does not get overwritten but adden.</p>
  <p><strong>Example</strong></p>
  <ul>
  <li>First run - color: red</li>
  <li>Second run: - color: green</li>
  </ul>
  <p>The importer sums the properties up, So the color has then multiple values - red AND green.
  I want to solve this by deleting the product properties before the importer runs by this code:</p>
  <pre><code>$items = $this-&gt;productPropertyRepository-&gt;search((new Criteria())-&gt;addFilter(new EqualsAnyFilter('productId',
          $productIds)), Context::createDefaultContext());
  
  $ids = [];
  foreach ($items as $item) {
      $ids[] = ['productId' =&gt; $item['product_id'], 'productVersionId' =&gt; $item['product_version_id']];
  }
  if ($ids) {
      $this-&gt;productPropertyRepository-&gt;delete($ids, Context::createDefaultContext());
  }
  </code></pre>
  <p>But this does not work because there is no <code>ProductPropertyEntity</code> class in Shopware 6.
  I get an exception when execution the first line.</p>
  <blockquote>
  <p>[Shopware\Core\Framework\DataAbstractionLayer\Exception\MappingEntityClassesException]<br />
  Mapping definition neither have entities nor collection.</p>
  </blockquote>
  <p>Whats the best way to avoid keeping orphaned data in this case?</p>