[BUG] Metadata returns an empty list instead of being empty

[alexlovelltroy]

After adding a group to the cloud-init server that only contains user-data information (and not meta-data) information, the group ends up represented in the meta-data anyway as a key and empty list.

$curl -s $CLOUD_INIT_URL/x1000c1s7b1n0/meta-data
groups:
  ssh: []

In the above example ssh should not be listed if it is empty.

groups should also not be listed if it is empty.

[davidallendj]

Would this simply require exporting the groups field and adding field tag to this line? https://github.com/OpenCHAMI/cloud-init/blob/main/internal/memstore/ciMemStore.go#L24

So something like:

type MemStore struct {
    list   map[string]citypes.CI
    Groups map[string]citypes.GroupData `json:"groups,omitempty"`
}