Looks like the only way to change the footer of that page is to edit the ErrorReportValve source code.
Thanks Peter for your reply. It shows me where to look into. The code recompilation often is not an option, but tracking references in JBossWeb source code I have found that sever info value is taken from:
which is located in:
Changing server.info property gives specified value in the error message (jar repackaging is a less interference that recompiling a class). The side effect is that everywhere where server info value it taken (e.g. in logs) our changed value is used.
That part is taken from Tomcat. Do you think it's worth to report feature request (to have configurable value in error page) to its issue tracker (or I'm the only one with that need)?