When configured with a context path of "", Undertow 1.1.3 changes the
context path to be "/". The change [1] was made to fix UNDERTOW-350
[2].

[1] https://github.com/undertow-io/undertow/commit/3db7707b8b34095d8d2fafecf94a10d101c62320
[2] https://issues.jboss.org/browse/UNDERTOW-350

See gh-2732