What version of AS7 / WildFly?
Thank you for your answer!
The version of Wildfly on our test environment is
.Final. On production we are with wildfly-8.1.0.Final. The problem appears on both environments.
The version of RestEasy is 3.0.8
try setting "url-charset" on http-listener (or what ever listener you use to access application)
<http-listener ... url-charset="windows-1250" ..../>
for example, but use charset you need.
also try setting
<servlet-container name="default" use-listener-encoding="true" default-encoding="utf-8" ...>
this is all in undertow subsystem configuration that you can find in standalone.xml