Web.Show_Document(URL, Target) doesn't work

Web.Show_Document(URL, Target) does not bring up the page in the web browser (without any error message).
When I try on Oracle Java Web Start then it works. Is it implemented?
My version: Red Hat WebStart Launcher 1.8.0.352.2

Edit:
The first parameter (url) contains characters like "<" that are not converted to hexadecimal - in this case "%3C". In Java Oracle this is not a problem but in OpenJDK/OpenWebStart it is.
Can you verify this?