Caveats are restrictions, yet empty Caveats mean "nothing's allowed"

This feels contrary to what Caveats are meant to express.

Both
```json
{"dns:example.com?TYPE=TXT": {
    "crud/create": [{}]
  }}
```
and
```json
{"dns:example.com?TYPE=TXT": {
    "crud/create": []
  }}
```
Intuitively, to me, mean that nothing's restricted.
Whereas if somebody wish to express "nothing's allowed" they could simply not include the capability in the first place.