public function messageThreads(int $offset = 0, int $limit = 20) : object
    {
        if ($this->messageThreads === null) {
            $response = $this->httpClient()->get(MessageThread::MESSAGE_THREAD_ENDPOINT . 'threads/', [
                'fields' => 'threadMembers',
                'limit' => $limit,
                'offset' => $offset,
                'sinceReceivedDate' => '1970-01-01T00:00:00Z' // Don't hardcode
            ]);

            $this->messageThreads = $response;
        }
        return $this->messageThreads;
    }