In soapUI 5.2.2 I have to use a property or modify the xml file directly to be able to test against a URL with mixed case it should just be allowed. Refer to Question on How for the the workarou...
I believe that sourceforge.net may be not the right place any more from my understand as SoapUI source has been moved / relocated to github which might allow to create issue there. Of course, looking forward to hear from TanyaYatskovska.
For those do not aware workaround for this issue:
By the way, there is simple & clean workaround for this issue if property expansion for the url is used, where capital letter can be supplied which won't be replaced to small.