I have a setup where I have my own variant of a ProxyHandler within undertow.

In one case, I proxy requests towards an IIS running MailEnable - if I try to download a webmail attachment where the filename contains non-ascii characters, MailEnable sends the filename in UTF-8 characters in the HTTP header.

I guess this is kinda a violation of the HTTP protocol, but thats how it is.

When I run my undertow proxy using HTTP1.1 between the browser and undertow, everything works as expected - the browser detects and supports UTF-8 characters in the filename in the HTTP headers.

But, if I run HTTP/2 between the browser and undertow, using Chrome I am getting an SPDY_PROTOCOL_ERROR displayed within chrome.

So, I guess that it is because Chrome chokes on the UTF-8 characters in the HTTP/2 headers - I tried digging into the spec but I cannot really find anything mentioned there regarding restrictions on header content - just on header naming.

Any suggestions ? I could of course strip the invalid characters from the response header before forwarding them but wanted to check if there is a better way first....
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