Traits/Document/Attributable.php
public function getAttributeInGroup($group, $key)
    {
        if (isset($this->attributes[$group][$key])) {
            return $this->attributes[$group][$key];
        }

        return null;
    }
public function getAttributeInGroup($group, $key)
    {
        if (isset($this->attributes[$group][$key])) {
            return $this->attributes[$group][$key];
        }

        return null;
    }
Get attribute by group and key. It will return null if doesn't exists

@param array $group
@param string $key

@return string|null