kkolinko review of fix for https://issues.apache.org/bugzilla/show_bug.cgi?id=57215
Don't return the uri if things go wrong. Given that the error states in question should never happen, throw an ISE instead.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1644529 13f79535-47bb-0310-9956-ffa450edef68