NPE in ApacheHttpClient43Test because cache is null in MediaTypeMap

ERROR [io.undertow.request] (default task-1) UT005023: Exception handling request to /ApacheHttpClient43Test/test: org.jboss.resteasy.spi.UnhandledException: java.lang.Nu
llPointerException
        at org.jboss.resteasy.core.ExceptionHandler.handleException(ExceptionHandler.java:381)
        at org.jboss.resteasy.core.SynchronousDispatcher.writeException(SynchronousDispatcher.java:218)
        at org.jboss.resteasy.core.SynchronousDispatcher.writeResponse(SynchronousDispatcher.java:614)
        at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:524)
        at org.jboss.resteasy.core.SynchronousDispatcher.lambda$invoke$4(SynchronousDispatcher.java:261)
        at org.jboss.resteasy.core.SynchronousDispatcher.lambda$preprocess$0(SynchronousDispatcher.java:161)
        at org.jboss.resteasy.core.interception.jaxrs.PreMatchContainerRequestContext.filter(PreMatchContainerRequestContext.java:364)
        at org.jboss.resteasy.core.SynchronousDispatcher.preprocess(SynchronousDispatcher.java:164)
        at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:247)
        at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.service(ServletContainerDispatcher.java:249)
        at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:60)
        at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:55)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:590)
        at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:74)
        at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62)
        at io.undertow.servlet.handlers.ServletChain$1.handleRequest(ServletChain.java:68)
        at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
        at org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)
        at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
        at io.undertow.servlet.handlers.RedirectDirHandler.handleRequest(RedirectDirHandler.java:68)
        ...
Caused by: java.lang.NullPointerException
        at org.jboss.resteasy.core.MediaTypeMap.getPossible(MediaTypeMap.java:589)
        at org.jboss.resteasy.core.providerfactory.ResteasyProviderFactoryImpl.resolveMessageBodyWriter(ResteasyProviderFactoryImpl.java:1272)
        at org.jboss.resteasy.core.providerfactory.ResteasyProviderFactoryImpl.getMessageBodyWriter(ResteasyProviderFactoryImpl.java:1253)
        at org.jboss.resteasy.core.ServerResponseWriter.lambda$writeNomapResponse$3(ServerResponseWriter.java:117)
        at org.jboss.resteasy.core.interception.jaxrs.ContainerResponseContextImpl.filter(ContainerResponseContextImpl.java:404)
        at org.jboss.resteasy.core.ServerResponseWriter.executeFilters(ServerResponseWriter.java:252)
        at org.jboss.resteasy.core.ServerResponseWriter.writeNomapResponse(ServerResponseWriter.java:101)
        at org.jboss.resteasy.core.ServerResponseWriter.writeNomapResponse(ServerResponseWriter.java:74)
        at org.jboss.resteasy.core.SynchronousDispatcher.writeResponse(SynchronousDispatcher.java:594)
        ... 52 more