Relay spec: start/endCursor nonNull conflicts with when there are no results

the Relay spec says:
` It must also contain fields startCursor and endCursor, both of which return non-null opaque strings.`

But it doesn't explain what to do when there are no results

the only two realistic options I see are returning a garbage cursor or breaking spec and returning null

Graphql-Relay-JS chooses to ignore the spec and return null
https://github.com/graphql/graphql-relay-js/blob/3796e0904fbfe0dd86e540d5b4df236330c8a5e7/src/connection/arrayConnection.ts

As does Java:
https://github.com/graphql-java/graphql-java/blob/1ee9630c7d25ccb55a5b1d9b1ccf7bf7895a8c7f/src/main/java/graphql/relay/Relay.java#L54

IMHO the spec should be updated to allow null for these values (as the ecosystem already ignore it)