Exception when accessing Topology via RESTCONF

When running the openflowplugin distribution and

sudo mn --topo tree,2 --controller 'remote,ip=10.0.2.2:6633' --switch ovsk,protocols=OpenFlow13

I can see the Topology via the Adapter to the AD-SAL, but

When I attempt to access
GET
http://localhost:8080/restconf/operational/network-topology:network-topology/topology/flow:1/

I get an exception:

java.lang.NullPointerException
org.opendaylight.yangtools.yang.data.impl.codec.xml.XmlDocumentUtils.writeValueByType(XmlDocumentUtils.java:157)
org.opendaylight.yangtools.yang.data.impl.codec.xml.XmlDocumentUtils.createXmlRootElement(XmlDocumentUtils.java:89)
org.opendaylight.yangtools.yang.data.impl.codec.xml.XmlDocumentUtils.createXmlRootElement(XmlDocumentUtils.java:110)
org.opendaylight.yangtools.yang.data.impl.codec.xml.XmlDocumentUtils.createXmlRootElement(XmlDocumentUtils.java:110)
org.opendaylight.yangtools.yang.data.impl.codec.xml.XmlDocumentUtils.toDocument(XmlDocumentUtils.java:73)
org.opendaylight.controller.sal.rest.impl.XmlMapper.write(XmlMapper.java:58)
org.opendaylight.controller.sal.rest.impl.StructuredDataToXmlProvider.writeTo(StructuredDataToXmlProvider.java:61)
org.opendaylight.controller.sal.rest.impl.StructuredDataToXmlProvider.writeTo(StructuredDataToXmlProvider.java:33)
com.sun.jersey.spi.container.ContainerResponse.write(ContainerResponse.java:306)
com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1479)
com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1391)
com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1381)
com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:416)
com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:538)
com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:716)
javax.servlet.http.HttpServlet.service(HttpServlet.java:848)
org.apache.catalina.filters.CorsFilter.handleNonCORS(CorsFilter.java:440)
org.apache.catalina.filters.CorsFilter.doFilter(CorsFilter.java:179)