[6.7] How to set header of DynamicImageResource ?

[smallufo]

Hi :
I wonder how to set header of DynamicImageResource ?
In 1.4 , it just override setHeaders(WebResponse response)
{
  response.setHeader("Cache-Control" , "no-cache");
}

But , how to do this in 6.7 ?

If I override setResponseHeaders(ResourceResponse data , Attributes
attributes) ,
It seems there are two ways to setHeader :

data.getHeaders().addHeader("Cache-Control", "no-cache");
and
((WebResponse) attributes.getResponse()).addHeader("Cache-Control" ,
"no-cache");

Which is correct ?

And...
in 1.4 , there is an "isCacheable()" method , where is it in 6.7 ?

Thanks .