Doing an HTTP get against a tree that has a node that contains an instanceidentifier who's value is null results in the following NPE:

ava.lang.NullPointerException
at org.opendaylight.yangtools.yang.data.util.AbstractStringInstanceIdentifierCodec.serialize(AbstractStringInstanceIdentifierCodec.java:40)
at org.opendaylight.yangtools.yang.data.codec.gson.JSONStringInstanceIdentifierCodec.serializeToWriter(JSONStringInstanceIdentifierCodec.java:50)
at org.opendaylight.yangtools.yang.data.codec.gson.JSONStringInstanceIdentifierCodec.serializeToWriter(JSONStringInstanceIdentifierCodec.java:19)
at org.opendaylight.yangtools.yang.data.codec.gson.JSONNormalizedNodeStreamWriter.writeValue(JSONNormalizedNodeStreamWriter.java:294)
at org.opendaylight.yangtools.yang.data.codec.gson.JSONNormalizedNodeStreamWriter.leafNode(JSONNormalizedNodeStreamWriter.java:195)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessAsSimpleNode(NormalizedNodeWriter.java:144)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:107)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:164)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:198)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:103)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:164)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter$OrderedNormalizedNodeWriter.writeMapEntryNode(NormalizedNodeWriter.java:248)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:183)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:103)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:164)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:213)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:103)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:164)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter$OrderedNormalizedNodeWriter.writeMapEntryNode(NormalizedNodeWriter.java:248)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:183)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:103)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:164)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:213)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:103)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.writeChildren(NormalizedNodeWriter.java:164)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.wasProcessedAsCompositeNode(NormalizedNodeWriter.java:180)
at org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter.write(NormalizedNodeWriter.java:103)
at org.opendaylight.controller.sal.rest.impl.NormalizedNodeJsonBodyWriter.writeTo(NormalizedNodeJsonBodyWriter.java:90)
at org.opendaylight.controller.sal.rest.impl.NormalizedNodeJsonBodyWriter.writeTo(NormalizedNodeJsonBodyWriter.java:43)
at com.sun.jersey.spi.container.ContainerResponse.write(ContainerResponse.java:306)
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1479)
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1391)
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1381)
at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:416)
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:538)
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:716)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:668)
at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:684)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1496)
at org.eclipse.jetty.servlets.CrossOriginFilter.handle(CrossOriginFilter.java:247)
at org.eclipse.jetty.servlets.CrossOriginFilter.doFilter(CrossOriginFilter.java:210)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1467)
at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:499)
at org.ops4j.pax.web.service.jetty.internal.HttpServiceServletHandler.doHandle(HttpServiceServletHandler.java:69)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:137)
at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:557)
at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:231)
at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1086)
at org.ops4j.pax.web.service.jetty.internal.HttpServiceContext.doHandle(HttpServiceContext.java:240)
at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:428)
at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:193)
at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1020)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:135)
at org.ops4j.pax.web.service.jetty.internal.JettyServerHandlerCollection.handle(JettyServerHandlerCollection.java:77)
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116)
at org.eclipse.jetty.server.Server.handle(Server.java:370)
at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:494)
at org.eclipse.jetty.server.AbstractHttpConnection.headerComplete(AbstractHttpConnection.java:971)
at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.headerComplete(AbstractHttpConnection.java:1033)
at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:644)
at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:235)
at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:82)
at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:667)
at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:52)
at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:608)
at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:543)
at java.lang.Thread.run(Thread.java:745)