I found the following regression issue running the code inside an ejb jar:
In the context of a search for a user for a user via the Wordpress REST API, I get e.g. following String:
This is achieved by a call of the UsersApi method listUsersAsString:
ResteasyWebTarget target = (ResteasyWebTarget)restEasy.target(uri);
The call rendering the result into a List<User> fails with error message in the subject.
The result is perfectly fine running Wildfly 11.Plain test cases with Wildfly 13 libraries is also fine. It seems to be a runtime configuration issue of RESTEasy in WIldfly 13.