I am defining a kubernetes service like this:

kind: Service
apiVersion: v1
metadata:
  name: de-identity-svc
  labels:
    app: api-identity
    environment: de
    product: api
  annotations:
    service.beta.kubernetes.io/aws-load-balancer-additional-resource-tags: "app=api-identity,environment=de,product=api"
    service.beta.kubernetes.io/aws-load-balancer-backend-protocol: http
    service.beta.kubernetes.io/aws-load-balancer-internal: 0.0.0.0/0
    service.beta.kubernetes.io/aws-load-balancer-type: nlb
spec:
  type: LoadBalancer
  selector:
    app: api-identity
    environment: de
  ports:
  - port: 80
    protocol: TCP

However, when the load balancer is created in AWS, it is created with type Classic instead of the expected network.

Edit

The kubernetes version info is this:

Client Version: version.Info{Major:"1", Minor:"8", GitVersion:"v1.8.4", GitCommit:"9befc2b8928a9426501d3bf62f72849d5cbcd5a3", GitTreeState:"clean", BuildDate:"2017-11-20T05:28:34Z", GoVersion:"go1.8.3", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"7", GitVersion:"v1.7.11", GitCommit:"b13f2fd682d56eab7a6a2b5a1cab1a3d2c8bdd55", GitTreeState:"clean", BuildDate:"2017-11-25T17:51:39Z", GoVersion:"go1.8.3", Compiler:"gc", Platform:"linux/amd64"}

Edit 2

As @vdMeent notes, this feature was added in Kubernetes 1.9 (https://aws.amazon.com/blogs/opensource/network-load-balancer-support-in-kubernetes-1-9/)