saveEntity example

      // the entity.       $item = [
        'target_id' => $fid,
        'alt' => $default_langcode . '_' . $fid . '_' . $this->randomMachineName(),
        'title' => $default_langcode . '_' . $fid . '_' . $this->randomMachineName(),
      ];
      $entity->{$this->fieldName}[] = $item;

      // Store the generated values keying them by fid for easier lookup.       $values[$default_langcode][$fid] = $item;
    }
    $entity = $this->saveEntity($entity);

    // Create some field translations for the test image field. The translated     // items will be one less than the original values to check that only the     // translated ones will be preserved. In fact we want the same fids and     // items order for both languages.     $translation = $entity->addTranslation($langcode);
    for ($delta = 0; $delta < $this->cardinality - 1; $delta++) {
      // Simulate a field reordering: items are shifted of one position ahead.       // The modulo operator ensures we start from the beginning after reaching       // the maximum allowed delta.       $index = ($delta + 1) % $this->cardinality;