Error: object or class could not be converted to string

[azatyar]

amocrm/amocrm-api-library/src/AmoCRM/Filters/EventsFilter.php:203
$filter['filter']['created_at'] = implode(',', $this->getCreatedAt());

Данная строка в коде дает ошибку:
Object of class AmoCRM\Filters\BaseRangeFilter could not be converted to string

Исправляется так:
$filter['filter']['created_at'] = $this->getCreatedAt();