Duplicate `BackendRefs` in `HTTPRoute` rules

[mlavacca]

What happened:

When converting Ingresses with the same rules into Gateway API objects, HTTPRoute Matches are properly grouped, while rule BackendRefs are duplicated.

What you expected to happen:

How to reproduce it (as minimally and precisely as possible):

the conversion output of the following yaml file:

---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: ingressa
  namespace: migration
  annotations:
    konghq.com/strip-path: "true"
spec:
  ingressClassName: kong
  rules:
  - http:
      paths:
      - path: /mia
        pathType: Prefix
        backend:
          service:
            name: mia
            port:
              number: 80
---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: ingressb
  namespace: migration
  annotations:
    konghq.com/strip-path: "true"
spec:
  ingressClassName: kong
  rules:
  - http:
      paths:
      - path: /mia
        pathType: Prefix
        backend:
          service:
            name: mia
            port:
              number: 80

is

apiVersion: gateway.networking.k8s.io/v1beta1
kind: Gateway
metadata:
  creationTimestamp: null
  name: kong
  namespace: migration
spec:
  gatewayClassName: kong
  listeners:
  - name: http
    port: 80
    protocol: HTTP
status: {}
---
apiVersion: gateway.networking.k8s.io/v1beta1
kind: HTTPRoute
metadata:
  creationTimestamp: null
  name: ingressA-all-hosts
  namespace: migration
spec:
  parentRefs:
  - name: kong
  rules:
  - backendRefs:
    - name: mia
      port: 80
    - name: mia
      port: 80
    matches:
    - path:
        type: PathPrefix
        value: /mia
status:
  parents: []

Anything else we need to know?:

[LiorLieberman]

/triage accepted

[LiorLieberman]

/good-first-issue

[k8s-ci-robot]

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[pottekkat]

@LiorLieberman Can I take up this issue? I haven't contributed to the Gateway API before, but I want to get involved, and this is a good place to start.

[LiorLieberman]

Hey @pottekkat, would be great to have you!

I think it is an awesome place to start.
Lets double check that @mlavacca was not already doing it.

@mlavacca are you good with @pottekkat taking this? if yes - assign it to them.

[mlavacca]

Hi @pottekkat, it's great to have you on this one!

/assign @pottekkat

[LiorLieberman]

Thanks @mlavacca.

@pottekkat let us know if you need any help!

[pottekkat]

Thank you @mlavacca @LiorLieberman . I will let you know if I have any questions or need help.

[pottekkat]

@LiorLieberman Unrelated, but it might be time for a new release. It seems like it has been a while since the last release, and a lot has changed since then.

[LiorLieberman]

Thanks @pottekkat. We are waiting on a few more changes to get in first.