Unable to instantiate a new object for FQN @aws-cdk/aws-ec2.VpcNetworkRef: null

[dsilvasc]

Hi, I'm using the JVM CDK and I'm running into a JsiiException when calling VpcNetworkRef.import_.

Minimal example in Scala:

import java.util

import scala.collection.JavaConverters._
import software.amazon.awscdk.{Construct, Environment, Stack, StackProps, App => CApp}
import software.amazon.awscdk.services.ec2.{
  AmazonLinuxImage,
  AutoScalingGroup,
  AutoScalingGroupProps,
  InstanceType,
  VpcNetworkId,
  VpcNetworkRef,
  VpcNetworkRefProps,
  VpcSubnetId
}

object SharedInfra {
  def vpc(parent: Construct): VpcNetworkRef = {
    val props = VpcNetworkRefProps.builder
      .withVpcId(new VpcNetworkId("test-vpc-id"))
      .withAvailabilityZones(util.Arrays.asList("us-east-1a"))
      .withPublicSubnetIds(util.Arrays.asList(new VpcSubnetId("test-public-id")))
      .withPrivateSubnetIds(util.Arrays.asList(new VpcSubnetId("test-private-id")))
      .build()
    VpcNetworkRef.import_(parent, "SharedInfraVPC", props)
  }
}

case class DemoStack(app: CApp, stackName: String, stackProps: StackProps, instanceType: String = "t2.medium")
    extends Stack(app, stackName, stackProps) {

  private val vpc = SharedInfra.vpc(this)

  new AutoScalingGroup(
    app,
    "Compute",
    AutoScalingGroupProps.builder
      .withInstanceType(new InstanceType(instanceType))
      .withMachineImage(new AmazonLinuxImage())
      .withVpc(vpc)
      .build()
  )
}

object DemoCDKSynthApp {
  def main(args: Array[String]): Unit = {
    val app = new software.amazon.awscdk.App
    val props = StackProps.builder.withEnv(Environment.builder.withRegion("us-east-1").build()).build()
    val stack = DemoStack(app, "demo-cdk", props)
    val output = app.synthesizeStack(stack.getName)
    println(output.getTemplate)
  }
}

Running it yields:

Exception in thread "main" software.amazon.jsii.JsiiException: Unable to instantiate a new object for FQN @aws-cdk/aws-ec2.VpcNetworkRef: null
	at software.amazon.jsii.JsiiEngine.createNative(JsiiEngine.java:252)
	at software.amazon.jsii.JsiiEngine.nativeFromObjRef(JsiiEngine.java:140)
	at software.amazon.jsii.JsiiObjectMapper.treeToValue(JsiiObjectMapper.java:111)
	at software.amazon.jsii.JsiiObject.jsiiStaticCall(JsiiObject.java:85)
	at software.amazon.awscdk.services.ec2.VpcNetworkRef.import_(VpcNetworkRef.java:14)
	at demo.cdk.SharedInfra$.vpc(DemoCDKApp.scala:63)
	at demo.cdk.DemoStack.<init>(DemoCDKApp.scala:70)
	at demo.cdk.DemoCDKSynthApp$.main(DemoCDKApp.scala:100)
	at demo.cdk.DemoCDKSynthApp.main(DemoCDKApp.scala)

The exception is InstantiationExceptionConstructorAccessorImpl and that line in JsiiEngine.java is:

                JsiiObject newObj = (JsiiObject)ctor.newInstance(InitializationMode.Jsii);

where ctor is protected software.amazon.awscdk.services.ec2.VpcNetworkRef(software.amazon.jsii.JsiiObject$InitializationMode).

The class VpcNetworkRef is abstract, so that might be the issue.

[rix0rrr]

@mpiroc @costleya @eladb

[eladb]

@dsilvasc I think you are right. Seems like an issue with the fact that the method return type is abstract.

Tracking in aws/jsii#220