Symptom: The provider class, class com.sun.jersey.core.impl.provider.xml.SAXParserContextProvider, could not be instantiated
pom.xml file likely has a compile (not test) dependency on jersey version 1.1.2-ea
http://jersey.576304.n2.nabble.com/Jersy-in-Jetty-Exceptions-td3481925.html suggests that different versions of jersey-core are involved in this problem.
Solution: Changing the jersey version 1.1.2 to 1.1.0 makes the error go away.
It's not clear what version of jersey is shipped with JIRA.