Neomerx\JsonApi\Document\Document::getDocument PHP Method

    public function getDocument()
    {
        if ($this->errors !== null) {
            return [self::KEYWORD_ERRORS => $this->errors];
        }
        $document = array_filter([self::KEYWORD_JSON_API => $this->version, self::KEYWORD_META => $this->meta, self::KEYWORD_LINKS => $this->links, self::KEYWORD_DATA => true, self::KEYWORD_INCLUDED => empty($this->included) === true ? null : array_values($this->included)], function ($value) {
            return $value !== null;
        });
        if ($this->showData === true) {
            $isDataNotArray = $this->isDataArrayed === false && empty($this->data) === false;
            $document[self::KEYWORD_DATA] = $isDataNotArray ? $this->data[0] : $this->data;
        } else {
            unset($document[self::KEYWORD_DATA]);
        }
        return $document;
    }