Relay pagination: endcursor is null but should be of type non-null

### Version Information

Server Version:
CLI Version (for CLI related issue): 2.30.1

### Environment

Cloud

### What is the current behaviour?

We are using pagination with Hasura Relay.

According to schema, `startCursor` and `endCursor` should be of type.kind "Non Null".

However, when the query runs out of results at the end of the pagination, the response is:

```
"data": {
"query_connection": {
"edges": [],
"pageInfo": {
"hasNextPage": false,
"endCursor": null
}
}
}
}
```

Our frontend GraphQl client throws an error:

`Suppressed: com.apollographql.apollo3.exception.JsonDataException: Expected a string but was NULL at path data.getforyoupage_connection.pageInfo.endCursor`

### What is the expected behaviour?

According to schema, we should return a `null` value but rather an empty string.

How to solve this?

No source file or test is named in the issue. Start by reproducing the Hasura Relay pagination query with no remaining results and inspect the pageInfo response. Done means the endCursor response matches the declared schema and no longer causes the reported GraphQL client error.

Written by the indexing model from the issue text.