DynamoDB querying GSI, page.lastEvaluatedKey returns non-null/ non-empty key when there are no more items to be retrieved.

I have Project Table with a GSI on the userID.

For a user say TestUser, I have 10 projects in my Dynamo Table/ the GSI FilterByUserID.

I'm using awssdk QueryEnhancedRequest for my query to get these projects:

QueryEnhancedRequest.Builder requestBuilder = QueryEnhancedRequest.builder(); requestBuilder .exclusiveStartKey(<startKey> ) .queryConditional(<Query condition matching the PK of the GSI>) .limit(10) .build();

I then subscribe the pages using

SdkPublisher<Page<Project>> publisher
subscribe(page -> {})

page.lastEvaluatedKey() in this case is expected to be null as the first page returns all the available 10 items/ projects we had in the DDB. But surprisingly page.lastEvaluatedKey() return the 10th item from the GSI that matched the key.

I'm wondering why this would happen, as per documentation https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Query.Pagination.html

A single Query only returns a result set that fits within the 1 MB size limit. To determine whether there are more results, and to retrieve them one page at a time, applications should do the following: Examine the low-level Query result:

1. If the result contains a LastEvaluatedKey element and it's non-null, proceed to step 2.
2. If there is not a LastEvaluatedKey in the result, there are no more items to be retrieved.

Any help to understand this scenario would be appreciated. Thanks