java.lang.AbstractMethodError: com.upload.swagger.ResourcesApp.render$default$2(Lorg/json4s/JsonAST$JValue;)Lorg/json4s/Formats in Swagger for uploadExample

[Aditya Pathak]

I am using the same upload example as given in the guide . Upload works fine but having trouble with the swagger api docs :

java.lang.AbstractMethodError: com.upload.swagger.ResourcesApp.render$default$2(Lorg/json4s/JsonAST$JValue;)Lorg/json4s/Formats;
	at org.scalatra.json.NativeJsonOutput$class.writeJson(NativeJson.scala:31)
	at com.upload.swagger.ResourcesApp.writeJson(UploadSwagger.scala:11)
	at org.scalatra.json.JsonOutput$$anonfun$renderPipeline$1.applyOrElse(JsonOutput.scala:74)
	at scala.PartialFunction$OrElse.apply(PartialFunction.scala:162)
	at org.scalatra.json.JValueResult$$anonfun$org$scalatra$json$JValueResult$$renderToJson$1.applyOrElse(JValueResult.scala:26)
	at scala.PartialFunction$OrElse.applyOrElse(PartialFunction.scala:165)
	at scala.PartialFunction$Lifted.apply(PartialFunction.scala:218)
	at scala.PartialFunction$Lifted.apply(PartialFunction.scala:214)
	at org.scalatra.ScalatraBase$class.loop$1(ScalatraBase.scala:414)
	at org.scalatra.ScalatraBase$class.renderResponseBody(ScalatraBase.scala:418)
	at com.upload.swagger.ResourcesApp.renderResponseBody(UploadSwagger.scala:11)
	at org.scalatra.ScalatraBase$class.renderResponse(ScalatraBase.scala:382)
	at com.upload.swagger.ResourcesApp.renderResponse(UploadSwagger.scala:11)
	at org.scalatra.ScalatraBase$class.executeRoutes(ScalatraBase.scala:201)
	at com.upload.swagger.ResourcesApp.executeRoutes(UploadSwagger.scala:11)
	at org.scalatra.ScalatraBase$$anonfun$handle$1.apply$mcV$sp(ScalatraBase.scala:126)
	at org.scalatra.ScalatraBase$$anonfun$handle$1.apply(ScalatraBase.scala:126)
	at org.scalatra.ScalatraBase$$anonfun$handle$1.apply(ScalatraBase.scala:126)
	at scala.util.DynamicVariable.withValue(DynamicVariable.scala:57)
	at org.scalatra.DynamicScope$class.withResponse(DynamicScope.scala:78)
	at com.upload.swagger.ResourcesApp.withResponse(UploadSwagger.scala:11)
	at org.scalatra.DynamicScope$$anonfun$withRequestResponse$1.apply(DynamicScope.scala:58)
	at scala.util.DynamicVariable.withValue(DynamicVariable.scala:57)
	at org.scalatra.DynamicScope$class.withRequest(DynamicScope.scala:69)
	at com.upload.swagger.ResourcesApp.withRequest(UploadSwagger.scala:11)
	at org.scalatra.DynamicScope$class.withRequestResponse(DynamicScope.scala:57)
	at com.upload.swagger.ResourcesApp.withRequestResponse(UploadSwagger.scala:11)
	at org.scalatra.ScalatraBase$class.handle(ScalatraBase.scala:125)
	at com.upload.swagger.ResourcesApp.org$scalatra$servlet$ServletBase$$super$handle(UploadSwagger.scala:11)
	at org.scalatra.servlet.ServletBase$class.handle(ServletBase.scala:53)
	at com.upload.swagger.ResourcesApp.org$scalatra$CorsSupport$$super$handle(UploadSwagger.scala:11)
	at org.scalatra.CorsSupport$$anonfun$handle$1.apply$mcV$sp(CORSSupport.scala:212)
	at org.scalatra.CorsSupport$$anonfun$handle$1.apply(CORSSupport.scala:200)
	at org.scalatra.CorsSupport$$anonfun$handle$1.apply(CORSSupport.scala:200)
	at scala.util.DynamicVariable.withValue(DynamicVariable.scala:57)
	at org.scalatra.DynamicScope$class.withResponse(DynamicScope.scala:78)
	at com.upload.swagger.ResourcesApp.withResponse(UploadSwagger.scala:11)
	at org.scalatra.DynamicScope$$anonfun$withRequestResponse$1.apply(DynamicScope.scala:58)
	at scala.util.DynamicVariable.withValue(DynamicVariable.scala:57)
	at org.scalatra.DynamicScope$class.withRequest(DynamicScope.scala:69)
	at com.upload.swagger.ResourcesApp.withRequest(UploadSwagger.scala:11)
	at org.scalatra.DynamicScope$class.withRequestResponse(DynamicScope.scala:57)
	at com.upload.swagger.ResourcesApp.withRequestResponse(UploadSwagger.scala:11)
	at org.scalatra.CorsSupport$class.handle(CORSSupport.scala:199)
	at com.upload.swagger.ResourcesApp.handle(UploadSwagger.scala:11)
	at org.scalatra.ScalatraServlet$class.service(ScalatraServlet.scala:60)
	at com.upload.swagger.ResourcesApp.service(UploadSwagger.scala:11)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
	at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:751)
	at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:566)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
	at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:578)
	at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:221)
	at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1111)
	at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:498)
	at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:183)
	at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1045)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
	at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:199)
	at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:109)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:98)
	at org.eclipse.jetty.server.Server.handle(Server.java:461)
	at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:284)
	at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:244)
	at org.eclipse.jetty.io.AbstractConnection$2.run(AbstractConnection.java:534)
	at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:607)
	at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:536)
	at java.lang.Thread.run(Thread.java:745)

Any pointers will be helpful.