getOmissions example

    ]);
    if ($data instanceof ErrorCollection) {
      $document['errors'] = $this->normalizeErrorDocument($object, $format, $context);
    }
    else {
      // Add data.       $document['data'] = $this->serializer->normalize($data, $format, $context);
      // Add includes.       $document['included'] = $this->serializer->normalize($object->getIncludes(), $format, $context)->omitIfEmpty();
      // Add omissions and metadata.       $normalized_omissions = $this->normalizeOmissionsLinks($object->getOmissions(), $format, $context);
      $meta = !$normalized_omissions instanceof CacheableOmission
        ? array_merge($object->getMeta(), ['omitted' => $normalized_omissions->getNormalization()])
        : $object->getMeta();
      $document['meta'] = (new CacheableNormalization($normalized_omissions, $meta))->omitIfEmpty();
    }
    // Add document links.     $document['links'] = $this->serializer->normalize($object->getLinks(), $format, $context)->omitIfEmpty();
    // Every JSON:API document contains absolute URLs.     return CacheableNormalization::aggregate($document)->withCacheableDependency((new CacheableMetadata())->addCacheContexts(['url.site']));
  }

  

  public function __construct($data, IncludedData $includes, LinkCollection $links, array $meta = []) {
    assert($data instanceof TopLevelDataInterface || $data instanceof ErrorCollection);
    assert(!$data instanceof ErrorCollection || $includes instanceof NullIncludedData);
    $this->data = $data instanceof TopLevelDataInterface ? $data->getData() : $data;
    $this->includes = $includes->getData();
    $this->links = $data instanceof TopLevelDataInterface ? $data->getMergedLinks($links->withContext($this)) : $links->withContext($this);
    $this->meta = $data instanceof TopLevelDataInterface ? $data->getMergedMeta($meta) : $meta;
    $this->omissions = $data instanceof TopLevelDataInterface
      ? OmittedData::merge($data->getOmissions(), $includes->getOmissions())
      : $includes->getOmissions();
  }

  /** * Gets the data. * * @return \Drupal\jsonapi\JsonApiResource\Data|\Drupal\jsonapi\JsonApiResource\ErrorCollection * The data. */
  public function getData() {
    return $this->data;
  }