java - Spring. Redirect to external url in controller without encoding

Question

I am trying to make redirect to external URL in my controller:

return "redirect:" + url;

all works fine for common urls, but now I need to redirect for url which contain other url as parameter (partner program referrer url). I have configured CharacterEncodingFilter in my web.xml. And as I understand this filter encode my parameter url to UTF-8 characters ('http://' encoded to 'http%3A%2F%2F'). This throw error in partner program.

How can I avoid encoding url in my controller?

Perhaps my conclusions contain errors?