Thank you for your reply. This isn't my first encounter with okhttputils2, I use it for a lot of occasion, but first strange behaviour.
As I wrote and the code snippet shows also, there is in the j.errormessage not at all any error reason/errormessage, but the j.errormessage contains the whole and correct rss, what I wanted to download!
My question is about this strange case. What is the error, if download result is unsuccess, but no error message but a correct rss in j.errormessage? Is it a strange matter, isn't it?