NPE is thrown in server.log when running Sse tests

2017-10-25 15:09:33,013 INFO [org.jboss.as.server] (management-handler-thread - 1) WFLYSRV0009: Undeployed "SseCORSFilterTest.war" (runtime-name: "SseCORSFilterTest.war")
2017-10-25 15:09:33,059 INFO [org.jboss.as.server] (management-handler-thread - 3) WFLYSRV0236: Suspending server with no timeout.
2017-10-25 15:09:33,067 INFO [org.jboss.as.ejb3] (management-handler-thread - 3) WFLYEJB0493: EJB subsystem suspension complete
2017-10-25 15:09:33,086 INFO [org.jboss.as.server] (Management Triggered Shutdown) WFLYSRV0241: Shutting down in response to management operation 'shutdown'
2017-10-25 15:09:33,079 ERROR [org.jboss.resteasy.resteasy_jaxrs.i18n] (Thread-97) RESTEASY002030: Failed to write event org.jboss.resteasy.plugins.providers.sse.OutboundSseEventImpl@28b7a4b7: java.lang.RuntimeException: java.lang.RuntimeException: RESTEASY003940: Unable to instantiate MessageBodyReader
at org.jboss.resteasy.plugins.providers.RegisterBuiltin.register(RegisterBuiltin.java:46)
at org.jboss.resteasy.spi.ResteasyProviderFactory.getInstance(ResteasyProviderFactory.java:596)
at org.jboss.resteasy.plugins.providers.sse.SseEventProvider.writeTo(SseEventProvider.java:99)
at org.jboss.resteasy.plugins.providers.sse.SseEventProvider.writeTo(SseEventProvider.java:26)
at org.jboss.resteasy.plugins.providers.sse.SseEventOutputImpl.writeEvent(SseEventOutputImpl.java:146)
at org.jboss.resteasy.plugins.providers.sse.SseEventOutputImpl.send(SseEventOutputImpl.java:126)
at org.jboss.resteasy.plugins.providers.sse.SseEventOutputImpl.send(SseEventOutputImpl.java:113)
at org.jboss.resteasy.test.providers.sse.SseResource$3.run(SseResource.java:203)
Caused by: java.lang.RuntimeException: RESTEASY003940: Unable to instantiate MessageBodyReader
at org.jboss.resteasy.spi.ResteasyProviderFactory.processProviderContracts(ResteasyProviderFactory.java:1482)
at org.jboss.resteasy.spi.ResteasyProviderFactory.registerProvider(ResteasyProviderFactory.java:1452)
at org.jboss.resteasy.spi.ResteasyProviderFactory.registerProvider(ResteasyProviderFactory.java:1404)
at org.jboss.resteasy.plugins.providers.RegisterBuiltin.registerProviders(RegisterBuiltin.java:82)
at org.jboss.resteasy.plugins.providers.RegisterBuiltin.register(RegisterBuiltin.java:42)
... 7 more
Caused by: java.lang.RuntimeException: RESTEASY003325: Failed to construct public org.jboss.resteasy.plugins.providers.jaxb.JAXBElementProvider()
at org.jboss.resteasy.core.ConstructorInjectorImpl.construct(ConstructorInjectorImpl.java:162)
at org.jboss.resteasy.spi.ResteasyProviderFactory.createProviderInstance(ResteasyProviderFactory.java:2238)
at org.jboss.resteasy.spi.ResteasyProviderFactory.addMessageBodyReader(ResteasyProviderFactory.java:818)
at org.jboss.resteasy.spi.ResteasyProviderFactory.processProviderContracts(ResteasyProviderFactory.java:1477)
... 11 more
Caused by: java.lang.NullPointerException
at io.undertow.servlet.spec.ServletContextImpl.getInitParameter(ServletContextImpl.java:421)
at org.jboss.resteasy.plugins.server.servlet.ListenerBootstrap.getParameter(ListenerBootstrap.java:102)
at org.jboss.resteasy.plugins.server.servlet.ServletBootstrap.getParameter(ServletBootstrap.java:38)
at org.jboss.resteasy.plugins.providers.jaxb.AbstractJAXBProvider.<init>(AbstractJAXBProvider.java:54)
at org.jboss.resteasy.plugins.providers.jaxb.JAXBElementProvider.<init>(JAXBElementProvider.java:46)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at org.jboss.resteasy.core.ConstructorInjectorImpl.construct(ConstructorInjectorImpl.java:150)
... 14 more

2017-10-25 15:09:33,130 INFO [org.wildfly.extension.messaging-activemq] (MSC service thread 1-6) WFLYMSGAMQ0006: Unbound messaging object to jndi name java:jboss/DefaultJMSConnectionFactory
2017-10-25 15:09:33,129 INFO [org.jboss.as.connector.subsystems.datasources] (MSC service thread 1-1) WFLYJCA0010: Unbound data source [java:jboss/datasources/ExampleDS]
2017-10-25 15:09:33,148 INFO [org.jboss.as.connector.deployment] (MSC service thread 1-8) WFLYJCA0011: Unbound JCA ConnectionFactory [java:/JmsXA]
2017-10-25 15:09:33,155 INFO [org.wildfly.extension.messaging-activemq] (ServerService Thread Pool – 30) WFLYMSGAMQ0006: Unbound messaging object to jndi name java:/ConnectionFactory
2017-10-25 15:09:33,169 INFO [org.wildfly.extension.undertow] (MSC service thread 1-4) WFLYUT0019: Host default-host stopping
2017-10-25 15:09:33,193 INFO [org.wildfly.extension.undertow] (MSC service thread 1-7) WFLYUT0008: Undertow HTTPS listener https suspending
2017-10-25 15:09:33,195 INFO [org.wildfly.extension.undertow] (MSC service thread 1-7) WFLYUT0007: Undertow HTTPS listener https stopped, was bound to 127.0.0.1:8443
2017-10-25 15:09:33,201 INFO [org.jboss.as.clustering.infinispan] (ServerService Thread Pool – 30) WFLYCLINF0003: Stopped client-mappings cache from ejb container
2017-10-25 15:09:33,206 INFO [org.jboss.as.connector.deployers.jdbc] (MSC service thread 1-2) WFLYJCA0019: Stopped Driver service with driver-name = h2
2017-10-25 15:09:33,240 INFO [org.apache.activemq.artemis.ra] (ServerService Thread Pool – 3) AMQ151003: resource adaptor stopped
2017-10-25 15:09:33,291 ERROR [org.jboss.resteasy.resteasy_jaxrs.i18n] (Thread-97) RESTEASY002030: Failed to write event org.jboss.resteasy.plugins.providers.sse.OutboundSseEventImpl@471ce908: javax.ws.rs.ServerErrorException: RESTEASY004082: No suitable message body writer for class : java.lang.String
at org.jboss.resteasy.plugins.providers.sse.SseEventProvider.writeTo(SseEventProvider.java:104)
at org.jboss.resteasy.plugins.providers.sse.SseEventProvider.writeTo(SseEventProvider.java:26)
at org.jboss.resteasy.plugins.providers.sse.SseEventOutputImpl.writeEvent(SseEventOutputImpl.java:146)
at org.jboss.resteasy.plugins.providers.sse.SseEventOutputImpl.send(SseEventOutputImpl.java:126)
at org.jboss.resteasy.plugins.providers.sse.SseEventOutputImpl.send(SseEventOutputImpl.java:113)
at org.jboss.resteasy.test.providers.sse.SseResource$3.run(SseResource.java:203)