public function convertTitle()
    {
        if ($this->title === null) {
            return '';
        }

        foreach ($this->splitWords() as $index => $word) {
            if ($this->wordShouldBeUppercase($index, $word)) {
                $this->rebuildTitle($index, $this->uppercaseWord($word));
            }
        }

        return $this->title;
    }