In my code I use this class as Java entity for DynamoDB table:

@DynamoDbBean
@Data
public class RecordDynamoDB {
    private String id;
    private String customerIdHash;
    private OffsetDateTime expirationTime;

    @DynamoDbPartitionKey
    public String getId() {
        return id;
    }

    @DynamoDbSecondarySortKey(indexNames = {"expirationTime-index"})
    @DynamoDbConvertedBy(DynamoDBTimestampConverter.class)
    public OffsetDateTime getExpirationTime() {
        return expirationTime;
    }

    @DynamoDbSecondaryPartitionKey(indexNames = "customerIdHash-index")
    public String getCustomerIdHash() {
        return customerIdHash;
    }
}

This code allows we to look for the items with desired status and expiration time:

var attributeValueMap = Map.of(
        ":status", AttributeValue.fromS(Status.EXPIRED.getValue()),
        ":expirationTime", DATE_TIME_CONVERTER.transformFrom(now)
);

var scanRequest = ScanRequest.builder()
        .tableName(CONSENTS_TABLE_NAME)
        .filterExpression("expirationTime < :expirationTime AND grant.#status = :status")
        .expressionAttributeValues(attributeValueMap)
        .expressionAttributeNames(Map.of("#status", "status"))
        .build();

return dynamoDbClient.scan(scanRequest)
        .items()
        .stream()
        .map(recordTableSchema::mapToItem)
        .toList();

This code works. Now I want to use index in order to load data faster. I create GSI with customerIdHash used as partition key and expirationTime as sort key. Then I try this code:

var attributeValueMap = Map.of(
        ":status", AttributeValue.fromS(ConsentGrantStatus.EXPIRED.getValue()),
        ":expirationTime", DATE_TIME_CONVERTER.transformFrom(now)
);

DynamoDbIndex<ConsentRecordDynamoDB> index = table(CONSENTS_TABLE_NAME, ConsentRecordDynamoDB.class).index(CONSENTS_INDEX_NAME);

var expression = Expression.builder()
        .expression("expirationTime < :expirationTime AND grant.#status = :status")
        .expressionNames(Map.of("#status", "status"))
        .expressionValues(attributeValueMap)
        .build();
return index.scan(builder -> builder.filterExpression(expression))
        .stream()
        .map(Page::items)
        .flatMap(List::stream)
        .toList();

This code employing index.scan() doesn’t return any record. What am I doing wrong here?