如何在DynamoDB中使用Set <String>属性？

CreateTableRequest createTableRequest = new CreateTableRequest()
    .withTableName("myTable")
    .withAttributeDefinitions(
        new AttributeDefinition("id", ScalarAttributeType.N),
        new AttributeDefinition("mySet", ScalarAttributeType.SS))
    .withKeySchema(
        new KeySchemaElement("id", KeyType.HASH))
    .withProvisionedThroughput(
        new ProvisionedThroughput(5L, 5L));

dynamoDB.createTable(createTableRequest);

Set<String> mySet = new HashSet<>();
mySet.add("value1");
mySet.add("value2");
mySet.add("value3");

Item item = new Item()
    .withPrimaryKey("id", 1)
    .withStringSet("mySet", mySet);

table.putItem(item);

Map<String, AttributeValue> expressionAttributeValues = new HashMap<>();
expressionAttributeValues.put(":value", new AttributeValue().withS("value1"));

ScanRequest scanRequest = new ScanRequest()
    .withTableName("myTable")
    .withFilterExpression("contains(mySet, :value)")
    .withExpressionAttributeValues(expressionAttributeValues);

ScanResult scanResult = dynamoDB.scan(scanRequest);
List<Map<String, AttributeValue>> items = scanResult.getItems();