fix(dev): Use non-ambigous array syntax in OpenAPI tutorial

[provokateurin]

☑️ Resolves

nextcloud/openapi-extractor#33
nextcloud/openapi-extractor#168

This fix is fully backwards compatible, so we can already advertise it.

[provokateurin]

/backport to stable30

[provokateurin]

/backport to stable29

[provokateurin]

/backport to stable28

[come-nc]

list<empty> and array<empty> are the same thing, but okay.

[nickvergessen]

list and array are the same thing, but okay.

Only in PHP, it's problematic in JSON and therefore spills over to clients.
https://3v4l.org/42qO0 that is exactly where we are coming from

[come-nc]

list and array are the same thing, but okay.

Only in PHP, it's problematic in JSON and therefore spills over to clients. https://3v4l.org/42qO0 that is exactly where we are coming from

I did not write list and array but list<empty> and array<empty>. Both are [].

[provokateurin]

It's a bit easier to handle it this way though, then the checks for array<TYPE> are simpler.