I have created a shoot(kubernetes-cluster) using Garner v0.22.0 with kubernetes v1.14.0. My requirement is to enable dynamic audit configuration in the kubernetes cluster which requires adding "--audit-dynamic-configuration" option in kube-apiserver.

Since in normal kubernetes cluster(not using Gardner) I am able to edit kube-apiserver manifest file which is saved on path /etc/kubernetes/manifests/kube-apiserver.yaml directly and add all the required changes, I am not able to find anything similar when my cluster is setup using Garner. But I am not able to find any way to edit kube-apiserver when cluster(shoot) gets created using Gardner.

I have also looked into https://github.com/gardener/gardener/tree/0.22.0/charts/seed-controlplane/charts/kube-apiserver chart. In this chart's values.yaml there is option available "additionalParameters: []" to add extra option. But this option is not available in https://github.com/gardener/gardener/blob/0.22.0/example/90-shoot-aws.yaml shoots's yaml file. Since you can provide other kubeAPIServer's config using it and it works perfectly when I am trying to add additional feature gate in my kube-apiserver.