Error starting process instance via REST on eap

When I try to start a process via REST (for instance http://localhost:8080/kie-wb/rest/runtime/org.jbpm:HR:1.0/process/hiring/start) the REST API is able to start the process instance but is unable to build the response. I'm getting an error message:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<exception>
<status>FAILURE</status>
<url>http://localhost:8080/kie-wb/rest/runtime/org.jbpm:HR:1.0/process/hiring/start</url>
<message>IllegalAnnotationsException thrown with message '1 counts of IllegalAnnotationExceptions'</message>
...

The full trace: https://gist.github.com/pefernan/9683257