NullPointerException when annotations are unavailable (not defined or private)

[randers-bit]

Hello, today i found that when in akka http all endpoints are set as private or no annotations are defined generateSwaggerJson will throw NullPointerException.
I now know that it was my mistake, but debugging NPE was time consuming and misleading.

I had code similar to this:

@Path( "user" )
case class UserRoute(){

    def apiRoute: Route = pathPrefix( "user" ) {
        concat(
            path( "1" ) {
                get(firstApi)
            },
            path( "2" ) {
                get(secondApi)
            },            
        )
    }
    
    @GET
    @Path( "1" )
    private def firstApi: Route = {
        complete("Ok")
    }
    
    @GET
    @Path( "2" )
    private def secondApi: Route = {
        complete("Ok")
    }
     
}

I think custom error message like "No annotations found" would be better for future developers.

[pjfanning]

Please provide a full reproducible use case. Also note that I am abandoning Akka in favour of Pekko.

[pjfanning]

Even provide the stack trace. That partial example is not very useful

[randers-bit]

I was building on different machine reproduction without a similar result.
I copied code which i used and then i found something which caused NPE.
In my swagger generator class i had definition for removing unwanted generated classes.

override val unwantedDefinitions: Seq[ String ] = Seq( "Function1", "Function1RequestContextFutureRouteResult" )

On plain project after i added this and had definitions of endpoints as private then NPE is thrown.

24/03 19:12:18.946 -> [ERROR][SwaggerHttpService] Issue with creating swagger.json
java.lang.NullPointerException: null
	at com.github.swagger.akka.SwaggerGenerator.filteredSwagger(SwaggerHttpService.scala:119)
	at com.github.swagger.akka.SwaggerGenerator.filteredSwagger$(SwaggerHttpService.scala:116)
	at akka.swagger.example.SwaggerRoute.filteredSwagger(SwaggerRoute.scala:8)
	at com.github.swagger.akka.SwaggerGenerator.generateSwaggerJson(SwaggerHttpService.scala:88)
	at com.github.swagger.akka.SwaggerGenerator.generateSwaggerJson$(SwaggerHttpService.scala:86)
	at akka.swagger.example.SwaggerRoute.generateSwaggerJson(SwaggerRoute.scala:8)
	at akka.swagger.example.SwaggerRoute.$anonfun$apiRoute$3(SwaggerRoute.scala:35)
	at akka.http.scaladsl.server.directives.RouteDirectives.$anonfun$complete$1(RouteDirectives.scala:51)
	at akka.http.scaladsl.server.StandardRoute$$anon$1.apply(StandardRoute.scala:19)
	at akka.http.scaladsl.server.StandardRoute$$anon$1.apply(StandardRoute.scala:19)
	at akka.http.scaladsl.server.directives.ExecutionDirectives.$anonfun$handleExceptions$2(ExecutionDirectives.scala:32)
	at akka.http.scaladsl.server.directives.BasicDirectives.$anonfun$mapRequestContext$2(BasicDirectives.scala:45)
	at akka.http.scaladsl.server.directives.BasicDirectives.$anonfun$textract$2(BasicDirectives.scala:161)
	at akka.http.scaladsl.server.RouteConcatenation$RouteWithConcatenation.$anonfun$$tilde$2(RouteConcatenation.scala:47)
	at akka.http.scaladsl.util.FastFuture$.strictTransform$1(FastFuture.scala:40)
	at akka.http.scaladsl.util.FastFuture$.transformWith$extension(FastFuture.scala:44)
	at akka.http.scaladsl.util.FastFuture$.flatMap$extension(FastFuture.scala:25)
	at akka.http.scaladsl.server.RouteConcatenation$RouteWithConcatenation.$anonfun$$tilde$1(RouteConcatenation.scala:44)
	at akka.http.scaladsl.server.directives.BasicDirectives.$anonfun$mapRouteResultWith$2(BasicDirectives.scala:74)
	at akka.http.scaladsl.server.directives.BasicDirectives.$anonfun$textract$2(BasicDirectives.scala:161)
	at akka.http.scaladsl.server.directives.ExecutionDirectives.$anonfun$handleExceptions$2(ExecutionDirectives.scala:32)
	at akka.http.scaladsl.server.Route$.$anonfun$createAsyncHandler$1(Route.scala:110)
	at akka.stream.impl.fusing.MapAsyncUnordered$$anon$31.onPush(Ops.scala:1430)
	at akka.stream.impl.fusing.GraphInterpreter.processPush(GraphInterpreter.scala:542)
	at akka.stream.impl.fusing.GraphInterpreter.processEvent(GraphInterpreter.scala:496)
	at akka.stream.impl.fusing.GraphInterpreter.execute(GraphInterpreter.scala:390)
	at akka.stream.impl.fusing.GraphInterpreterShell.runBatch(ActorGraphInterpreter.scala:650)
	at akka.stream.impl.fusing.GraphInterpreterShell$AsyncInput.execute(ActorGraphInterpreter.scala:521)
	at akka.stream.impl.fusing.GraphInterpreterShell.processEvent(ActorGraphInterpreter.scala:625)
	at akka.stream.impl.fusing.ActorGraphInterpreter.akka$stream$impl$fusing$ActorGraphInterpreter$$processEvent(ActorGraphInterpreter.scala:800)
	at akka.stream.impl.fusing.ActorGraphInterpreter$$anonfun$receive$1.applyOrElse(ActorGraphInterpreter.scala:818)
	at akka.actor.Actor.aroundReceive(Actor.scala:537)
	at akka.actor.Actor.aroundReceive$(Actor.scala:535)
	at akka.stream.impl.fusing.ActorGraphInterpreter.aroundReceive(ActorGraphInterpreter.scala:716)
	at akka.actor.ActorCell.receiveMessage(ActorCell.scala:579)
	at akka.actor.ActorCell.invoke(ActorCell.scala:547)
	at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:270)
	at akka.dispatch.Mailbox.run(Mailbox.scala:231)
	at akka.dispatch.Mailbox.exec(Mailbox.scala:243)
	at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290)
	at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1020)
	at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1656)
	at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1594)
	at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:183)

When i changed firstApi to public from private then swagger.json is generated properly.

{
  "openapi" : "3.0.1",
  "info" : {
    "title" : "",
    "description" : "",
    "termsOfService" : "",
    "version" : ""
  },
  "servers" : [ {
    "url" : "http://localhost"
  } ],
  "security" : [ ],
  "paths" : {
    "/user/1" : {
      "get" : {
        "operationId" : "firstApi",
        "responses" : {
          "default" : {
            "description" : "default response",
            "content" : {
              "*/*" : {
                "schema" : {
                  "$ref" : "#/components/schemas/Function1RequestContextFutureRouteResult"
                }
              }
            }
          }
        }
      }
    }
  },
  "components" : {
    "schemas" : { }
  }
}

When both endpoints are private and unwantedDefinitions are removed then it generates properly.

{
  "openapi" : "3.0.1",
  "info" : {
    "title" : "",
    "description" : "",
    "termsOfService" : "",
    "version" : ""
  },
  "servers" : [ {
    "url" : "http://localhost"
  } ],
  "security" : [ ]
}

[randers-bit]

I'm writing this because this could be helpfull for pekko too maybe.

[randers-bit]

I did reproduction here https://github.com/Randerspl/akka-swagger-npe.
Just run it and enter localhost:9000/swagger and NPE should be thrown.