Download attachment via REST API, how to escape special characters like German umlauts or a ' + ' ?

Hi,

I try to download attachments via REST-API, using url:

http://<host>/qcbin/rest/domains/<domain>/projects/<project>/defects/<id>/attachments/<filename>

It works perfect with "normal" filenames. I escape space in filename with %20, # with %23, ...

But, if I got German umlauts, like "äöü" it does not help to escape them with %FC or similar.

I have the same problem, if the filename contains " + ", eg: "Test + a Name.png". This is escaped to "Test%20%2B%20a%20Name.png" but could not be downloaded.

Error is: HTTP_500 : No entity of type attachment with id Test  a Name.png exists. (so the + got eaten here).

Any body can help out here? How can I download attachments with characters like "äöü" in the filename?