ButtonAttributes::offsetSet

public function offsetSet($offset, $value)
{
	if($offset === null)
	{
		$this->attributes[] = $value;
	}
	else
	{
		$offset = mb_strtolower($offset);
		if (self::hasDataPrefix($offset))
		{
			$this->dataAttributes[self::deleteDataPrefix($offset)] = $value;
		}
		else
		{
			$this->attributes[$offset] = $value;
		}
	}
}