when i'm trying to use mod_cluster undertow filter with default locale set to sk_SK, everytime when advertise message is sent it is rejected by clustered server with messaqe "Advertise message digest verification failed for server..." (class org.jboss.modcluster.advertise.impl.AdvertiseListenerImpl)
message send by mod_cluster filter is: (class io.undertow.server.handlers.proxy.mod_cluster.MCMPAdvertiseTask)

HTTP/1.0 200 OK
Date: Št, 6 aug 2015 18:30:06 +0200
Sequence: 1
Digest: 8cf5a5ebf35667a01c7298db3fb7fdbe
Server: 970d1fd6-1df4-4115-b704-9fd7fe7cbeb8
X-Manager-Address: 127.0.0.1:8080
X-Manager-Url: /
X-Manager-Protocol: http
X-Manager-Host: 127.0.0.1

please notice character "Š" in date field.

When I switch to locale en_US, now the date field does not contains any non ASCII character, and clustering works as expected