quarkus-kubernetes generated Ingress broken in 2.0.0.CR3

Describe the bug

When using the quarkus-kubernetes extension, the generation of the Ingress when quarkus.kubernetes.ingress.expose=true is broken in 2.0.0.CR3. It works fine in 1.13.7.Final.

To Reproduce

I'm attaching a reproducer project which was created using the Quarkus Kubernetes Guide. When running ./mvnw clean package with the reproducer project, the Ingress that gets generated inside target/kubernetes/kubernetes.yml looks like

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  annotations:
    app.quarkus.io/build-timestamp: 2021-06-18 - 12:51:06 +0000
  labels:
    app.kubernetes.io/name: kubernetes-quickstart
    app.kubernetes.io/version: 1.0.0-SNAPSHOT
  name: kubernetes-quickstart
spec:
  rules:
    - http:
        paths:
          - backend:
              service:
                name: kubernetes-quickstart
                port:
                  name: http
            pathType: Prefix
    - http:
        paths:
          - backend:
              service:
                name: kubernetes-quickstart
                port:
                  name: http
            pathType: Prefix

When trying to deploy this to OpenShift/Kubernetes (via kubectl apply -f target/kubernetes/kubernetes.yml), this error is encountered:

$ kubectl apply -f target/kubernetes/kubernetes.yml
service/kubernetes-quickstart created
deployment.apps/kubernetes-quickstart created
The Ingress "kubernetes-quickstart" is invalid: 
* spec.rules[0].http.paths[0].path: Invalid value: "": must be an absolute path
* spec.rules[1].http.paths[0].path: Invalid value: "": must be an absolute path

When switching the project back to Quarkus version 1.13.7.Final and re-running ./mvnw clean package, the generated Ingress looks like

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  annotations:
    app.quarkus.io/build-timestamp: 2021-06-18 - 13:00:47 +0000
  labels:
    app.kubernetes.io/name: kubernetes-quickstart
    app.kubernetes.io/version: 1.0.0-SNAPSHOT
  name: kubernetes-quickstart
spec:
  rules:
  - host: ""
    http:
      paths:
      - backend:
          serviceName: kubernetes-quickstart
          servicePort: 8080
        path: /

It applies fine.

If I then add a value in the quarkus.kubernetes.ingress.host property, in 2.0.0.CR3 the Ingress looks like

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  annotations:
    app.quarkus.io/build-timestamp: 2021-06-18 - 13:08:27 +0000
  labels:
    app.kubernetes.io/name: kubernetes-quickstart
    app.kubernetes.io/version: 1.0.0-SNAPSHOT
  name: kubernetes-quickstart
spec:
  rules:
    - host: kubernetes-quickstart
      http:
        paths:
          - backend:
              service:
                name: kubernetes-quickstart
                port:
                  name: http
            pathType: Prefix
          - backend:
              service:
                name: kubernetes-quickstart
                port:
                  name: http

which is still invalid when trying to apply it:

$ kubectl apply -f target/kubernetes/kubernetes.yml 
service/kubernetes-quickstart created
deployment.apps/kubernetes-quickstart created
The Ingress "kubernetes-quickstart" is invalid: 
* spec.rules[0].http.paths[0].path: Invalid value: "": must be an absolute path
* spec.rules[0].http.paths[1].pathType: Required value: pathType must be specified

Reproducer project: kubernetes-quickstart.zip

Configuration

# Add your application.properties here, if applicable.
quarkus.kubernetes.ingress.expose=true
quarkus.container-image.registry=quay.io
quarkus.container-image.group=edeandrea
quarkus.container-image.build=true

Environment (please complete the following information):

Output of `uname -a` or `ver`

Darwin edeandre-mac 20.5.0 Darwin Kernel Version 20.5.0: Sat May  8 05:10:33 PDT 2021; root:xnu-7195.121.3~9/RELEASE_X86_64 x86_64

Output of `java -version`

openjdk version "11.0.2" 2019-01-15
OpenJDK Runtime Environment 18.9 (build 11.0.2+9)
OpenJDK 64-Bit Server VM 18.9 (build 11.0.2+9, mixed mode)

Quarkus version or git rev

1.13.7.Final vs 2.0.0.CR3

Build tool (ie. output of `mvnw --version` or `gradlew --version`)

Apache Maven 3.8.1 (05c21c65bdfed0f71a2f2ada8b84da59348c4c5d)
Maven home: /Users/edeandre/.m2/wrapper/dists/apache-maven-3.8.1-bin/2l5mhf2pq2clrde7f7qp1rdt5m/apache-maven-3.8.1
Java version: 11.0.2, vendor: Oracle Corporation, runtime: /Users/edeandre/.sdkman/candidates/java/11.0.2-open
Default locale: en_US, platform encoding: UTF-8
OS name: "mac os x", version: "10.16", arch: "x86_64", family: "mac"

https://github.com/quarkusio/quarkus/issues/18007

$upstream:18007$

snowdrop-zen / quarkus