getRelationships example

return $this->metaData;
    }

    protected function mergeRecords(Record $recordA, Record $recordB): void
    {
        foreach ($recordB->getAttributes() as $key => $value) {
            if (!empty($value)) {
                $recordA->setAttribute($key, $value);
            }
        }

        foreach ($recordB->getRelationships() as $key => $value) {
            if ($value['data'] === null) {
                continue;
            }
            $recordA->addRelationship($key, $value);
        }

        foreach ($recordB->getExtensions() as $key => $value) {
            if ($value['data'] === null) {
                continue;
            }
            $recordA->addExtension($key, $value);
        }

$this->addExtensions($fields, $serialized, $entity, $result);

        if ($isRelationship) {
            $result->addIncluded($serialized);
        } else {
            $result->addEntity($serialized);
        }
    }

    protected function serializeRelationships(ResponseFields $fields, Record $record, Entity $entity, JsonApiEncodingResult $result): void
    {
        $relationships = $record->getRelationships();

        foreach ($relationships as $propertyName => &$relationship) {
            $relationship['links']['related'] = $record->getLink('self') . '/' . $this->camelCaseToSnailCase($propertyName);

            try {
                /** @var Entity|EntityCollection<Entity>|null $relationData */
                $relationData = $entity->get($propertyName);
            } catch (\InvalidArgumentException) {
                continue;
            }