protected function incrementCurrentDateUntilValid()
    {
        $attempts = 0;

        do {
            $this->current = $this->current->add($this->dateInterval);

            $this->validationResult = null;

            if (++$attempts > static::NEXT_MAX_ATTEMPTS) {
                throw new RuntimeException('Could not find next valid date.');
            }
        } while ($this->validateCurrentDate() === false);
    }