Flarum\Api\Controller\ShowDiscussionController::getPostRelationships PHP Method

    private function getPostRelationships(array $include)
    {
        $prefixLength = strlen($prefix = 'posts.');
        $relationships = [];
        foreach ($include as $relationship) {
            if (substr($relationship, 0, $prefixLength) === $prefix) {
                $relationships[] = substr($relationship, $prefixLength);
            }
        }
        return $relationships;
    }