I am currently using Wildfly 8.1.0.Final and I am composing a few rules for URL Rewriting in undertow-handlers.conf.
I was unable to set case-insensitive flag [NC] (or any other flag) in undertow-handlers.conf file.

I got to know that the java class named: 'RegularExpressionPredicate.java' is responsible for parsing regexes, and this is not setting any flags (as seen here):

https://github.com/undertow-io/undertow/blob/master/core/src/main/java/io/undertow/predicate/RegularExpressionPredicate.java

Feature Request: Ability to set/unset flags.