- 'reply-to-uri' => defaults($activity, 'reply-to-id', ''),
- 'conversation-href' => defaults($activity, 'context', ''),
- 'conversation-uri' => defaults($activity, 'conversation', ''),
+ 'reply-to-uri' => $activity['reply-to-id'] ?? '',
+ 'conversation-href' => $activity['context'] ?? '',
+ 'conversation-uri' => $activity['conversation'] ?? '',