Null values ignored in HelmChartInflationGenerator

[erwanval]

What happened?

Since 5.4.0, there is a regression causing null values in helmChartInflationGenerator to be ignored.
Setting a null value is useful to remove default values present in values.yaml.

I have tried with all versions of kustomize since 5.0.0, and it seems it was fixed in 5.2.0, but reappeared in 5.4.0.

What did you expect to happen?

Setting a null value should overwrite and remove a default values present in values.yaml.

How can we reproduce it (as minimally and precisely as possible)?

# kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

generators:
  - helmchartinflation-crowdsec.yaml

# helmchartinflation-crowdsec.yaml
apiVersion: builtin
kind: HelmChartInflationGenerator
metadata:
  name: crowdsec
releaseName: crowdsec
namespace: crowdsec
name: crowdsec
repo: https://crowdsecurity.github.io/helm-charts
version: 0.13.0
includeCRDs: true
valuesInline:
  lapi:
    resources:
      requests:
        cpu: 10m
        memory: 100Mi
      limits:
        cpu: null # We want to remove the default from values.yaml
        memory: 100Mi
    persistentVolume:
      config:
        enabled: false
      data:
        enabled: false
  agent:
    resources:
      requests:
        cpu: 10m
        memory: 100Mi
      limits:
        cpu: null # We want to remove the default from values.yaml
        memory: 100Mi
    acquisition:
      - namespace: ingress-nginx
        podName: ingress-nginx-controller-*
        program: nginx

Expected output

apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: crowdsec-agent
spec:
  [...]
  template:
    [...]
    spec:
      [...]
      containers:
        [...]
          resources:
            limits:
              memory: 100Mi
            requests:
              cpu: 10m
              memory: 100Mi

Actual output

apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: crowdsec-agent
spec:
  [...]
  template:
    [...]
    spec:
      [...]
      containers:
        [...]
          resources:
            limits:
              cpu: 500m # default from values.yaml still set
              memory: 100Mi
            requests:
              cpu: 10m
              memory: 100Mi

Kustomize version

5.4.0

Operating system

None

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