7.Challenge Not yet complete... here's what's wrong: 
Ensure that you implement all the pagination methods using the corresponding StandardSetController methods.
/**
 * @name OrderExtension
 * @description This class is provided for you to facilitate the Super Badge
**/
public class OrderExtension {

    public Order orderRecord {get;set;}
    public List<OrderItem> orderItemList {get;set;}
    public String selectedFamily {get;set;}
    public List<chartHelper.chartData> pieData {get;set;}
    public Decimal total {get;set;}
  
    public Map<Id,OrderItem> orderItemMap;
    ApexPages.StandardSetController standardSetController;

    public OrderExtension(ApexPages.StandardController standardController){
        orderRecord = (Order)standardController.getRecord();
        orderItemMap = new Map<id,OrderItem>();
        if ( orderRecord.Id != null ){
            orderRecord = queryOrderRecord(orderRecord.Id);
        }
        orderItemList = new List<OrderItem>();
        OrderItemList.addAll(orderRecord.OrderItems);
        set<Id> p2ids = new set<Id>();
        for(OrderItem oitem : OrderItemList){
            p2ids.add(oitem.PriceBookEntryId);
        }
        List<PriceBookEntry> p2List = new List<PriceBookEntry>();
        if(p2Ids.size()>0){
            p2List = [select id from PriceBookEntry where id IN: p2Ids];
        }
        standardSetController= new ApexPages.StandardSetController(p2List);
        standardSetController.setPageSize(Constants.DEFAULT_ROWS);
     
    }
    

    public void resetstandardSetController() {
        String query = 'SELECT Name, Product2.Family, Product2.Name, Product2Id, UnitPrice, Product2.Quantity_Remaining__c'
                     + '  FROM PricebookEntry WHERE IsActive = TRUE';

        if (selectedFamily != null && selectedFamily != Constants.SELECT_ONE) {
            query += ' AND Product2.Family = \'' + selectedFamily + '\'';
        }
        query += ' ORDER BY Name';

        standardSetController= new ApexPages.StandardSetController(Database.getQueryLocator(query));
        if(StandardSetController== null){
            StandardSetController= new ApexPages.StandardSetController(Database.getQueryLocator([SELECT Product2Id, Product2.Family, Product2.Name, 
Product2.Quantity_Remaining__c, UnitPrice FROM PricebookEntry ]));
            StandardSetController.setPageSize(Constants.DEFAULT_ROWS);
        }
        
    }

    //ToDo: Implement your own method to populate orderItemList
    //  that you will call after pagination and/or family selection
   public void GetOrderItems() {
        orderItemList = new List<OrderItem>();
        for (SObject obj : standardSetController.getRecords()) {
            PricebookEntry pbe = (PricebookEntry)obj;

            if (orderItemMap.containsKey(pbe.Product2Id)) {
                orderItemList.add(orderItemMap.get(pbe.Product2Id));
            } else {
                orderItemList.add(new OrderItem(
                    PricebookEntryId=pbe.Id,
                    Product2Id=pbe.Product2Id,
                    UnitPrice=pbe.UnitPrice,
                    Quantity=0,
                    Product2=pbe.Product2
                ));
            }
        }
    }


    /**
     * @name OnFieldChange
     * @description
    **/
    public void onFieldChange(){
        //ToDo: Implement logic to store the values changed on the page
        for (OrderItem oi : orderItemList) {
            orderItemMap.put(oi.PricebookEntryId, oi);
        }

        //      and populate pieData
        pieData = null;
        total = 0;
        for (OrderItem oi : orderItemMap.values()) {
            if (oi.Quantity > 0) {
                if (null == pieData) {
                    pieData = new List<chartHelper.ChartData>();
                }
                pieData.add(new chartHelper.ChartData(oi.Product2.Name, oi.Quantity * oi.UnitPrice));
                //      and populate total
                total += oi.UnitPrice * oi.Quantity;
            }

        }

    }

    /**
     * @name SelectFamily
     * @description
    **/
    public void selectFamily(){
        //ToDo: Implement logic to filter based on the selected product family
        resetstandardSetController();
        GetOrderItems();
    }

    /**
     * @name Save
     * @description
    **/
    public void save(){
        //ToDo: Implement logic to save the Order and populated OrderItems
        System.Savepoint sp = Database.setSavepoint();
        try {
            if (null == orderRecord.Pricebook2Id) {
                orderRecord.Pricebook2Id = Constants.STANDARD_PRICEBOOK_ID;
            }
            upsert orderRecord;

            List<OrderItem> orderItemsToUpsert = new List<OrderItem>();
            List<OrderItem> orderItemsToDelete = new List<OrderItem>();
            system.debug('@@@@@@@@@@@@@@@#######'+orderItemMap.values());
            for (OrderItem oi : orderItemMap.values()) {
                if (oi.Quantity > 0) {
                    if (null == oi.OrderId) {
                        oi.OrderId = orderRecord.Id;
                    }
                    orderItemsToUpsert.add(oi);
                } else if (oi.Id != null) {
                    orderItemsToDelete.add(oi);
                }
            }
            if(orderItemsToUpsert.size()>0)
            upsert orderItemsToUpsert;
            if(orderItemsToDelete.size()>0)
            delete orderItemsToDelete;
        } catch (Exception e) {
            Database.rollback(sp);
            apexPages.addMessage(new ApexPages.message(ApexPages.Severity.INFO,Constants.ERROR_MESSAGE));
        }
    }


    /**
     * @name First
     * @description
    **/
    public void First(){      
       standardSetController.first();
       GetOrderItems();
    }

    /**
     * @name Next
     * @description
    **/
    public void Next(){   
       standardSetController.next();
        GetOrderItems();
    }

    /**
     * @name Previous
     * @description
    **/
    public void Previous(){      
        standardSetController.previous();
        GetOrderItems();
    }

    /**
     * @name Last
     * @description
    **/
    public void Last(){
        standardSetController.last();
        GetOrderItems();
    }
  /**
     * @name GetHasPrevious
     * @description
    **/
   public Boolean GetHasPrevious(){
        return standardSetController.gethasprevious();
    }

    /**
     * @name GetHasNext
     * @description
    **/
   public Boolean GetHasNext(){
        return standardSetController.gethasnext();
    }

    /**
     * @name GetTotalPages
     * @description
    **/
  public Integer GetTotalPages(){
        Integer totalPages = (Integer)Math.ceil(standardSetController.getResultSize() / (Decimal)Constants.DEFAULT_ROWS);
        System.debug('############ totalPages: ' + totalPages);
        return totalPages;
    }

    /**
    * @name GetPageNumber
     * @description
    **/
    public Integer GetPageNumber(){
        return standardSetController.getpagenumber();
    }

    /**
     * @name GetFamilyOptions
     * @description
    **/
    public List<SelectOption> GetFamilyOptions() {
        List<SelectOption> options = new List<SelectOption>{
            new SelectOption(Constants.SELECT_ONE, Constants.SELECT_ONE)
        };

        for (Schema.PicklistEntry ple : Constants.PRODUCT_FAMILY) {
            options.add(new SelectOption(ple.getValue(), ple.getLabel()));
        }
        return options;
    }
    

    /**
     * @name QueryOrderRecord
     * @description
    **/
    public static Order QueryOrderRecord(Id orderId){
     return [
        SELECT Id, AccountId, EffectiveDate, Name, Status, Pricebook2Id,
                (
                    SELECT Id, OrderId, Quantity, UnitPrice, PricebookEntryId, Product2Id,
                         Product2.Name, Product2.Family, Product2.Quantity_Remaining__c
                    FROM OrderItems where PricebookEntry.isActive = true
                )
            FROM Order WHERE Id = :orderId
            ];
    }

}

/**
* @name OrderExtension
* @description This class is provided for you to facilitate the Super Badge
**/
public class OrderExtension {
    
    public Order orderRecord {get;set;}
    public List<OrderItem> orderItemList {get;set;}
    public String selectedFamily {get;set;}
    public List<chartHelper.chartData> pieData {get;set;}
    public Decimal total {get;set;}
    public Map<Id,OrderItem> orderItemMap;
    ApexPages.StandardSetController standardSetController;
    public OrderExtension(ApexPages.StandardController standardController){
        orderRecord = (Order)standardController.getRecord();
        orderItemMap = new Map<id,OrderItem>();
        if ( orderRecord.Id != null ){
            orderRecord = queryOrderRecord(orderRecord.Id);
        }
        resetSsc();
        total = 0;
        for (OrderItem oi : orderRecord.OrderItems) {
            orderItemMap.put(oi.Product2Id, oi);
            if (oi.Quantity > 0) {
                if (null == pieData) {
                    pieData = new List<ChartHelper.ChartData>();
                }
                pieData.add(new chartHelper.ChartData(oi.Product2.Name, oi.Quantity * oi.UnitPrice));
                total += oi.UnitPrice * oi.Quantity;
            }
        }
        PopulateOrderItems();
    }
    void resetSsc() {
        String query = 'SELECT Name, Product2.Family, Product2.Name, Product2Id, UnitPrice, Product2.Quantity_Remaining__c'
            + '  FROM PricebookEntry WHERE IsActive = TRUE';
        if (selectedFamily != null && selectedFamily != Constants.SELECT_ONE) {
            query += ' AND Product2.Family = \'' + selectedFamily + '\'';
        }
        query += ' ORDER BY Name';
        standardSetController = new ApexPages.StandardSetController(Database.getQueryLocator(query));
        standardSetController.setPageSize(Constants.DEFAULT_ROWS);
    }
    //ToDo: Implement your own method to populate orderItemList
    //  that you will call after pagination and/or family selection
    void PopulateOrderItems() {
        orderItemList = new List<OrderItem>();
        for (SObject obj : standardSetController.getRecords()) {
            PricebookEntry pbe = (PricebookEntry)obj;
            
            if (orderItemMap.containsKey(pbe.Product2Id)) {
                orderItemList.add(orderItemMap.get(pbe.Product2Id));
            } else {
                orderItemList.add(new OrderItem(
                    PricebookEntryId=pbe.Id,
                    Product2Id=pbe.Product2Id,
                    UnitPrice=pbe.UnitPrice,
                    Quantity=0,
                    Product2=pbe.Product2
                ));
            }
        }
    }
    /**
* @name OnFieldChange
* @description
**/
    public void OnFieldChange(){
        //ToDo: Implement logic to store the values changed on the page
        for (OrderItem oi : orderItemList) {
            orderItemMap.put(oi.Product2Id, oi);
        }
        //      and populate pieData
        pieData = null;
        total = 0;
        for (OrderItem oi : orderItemMap.values()) {
            if (oi.Quantity > 0) {
                if (null == pieData) {
                    pieData = new List<chartHelper.ChartData>();
                }
                pieData.add(new chartHelper.ChartData(oi.Product2.Name, oi.Quantity * oi.UnitPrice));
                //      and populate total
                total += oi.UnitPrice * oi.Quantity;
            }
        }
    }
    /**
* @name SelectFamily
* @description
**/
    public void SelectFamily(){
        //ToDo: Implement logic to filter based on the selected product family
        resetSsc();
        PopulateOrderItems();
    }
    /**
* @name Save
* @description
**/
    public void Save(){
        //ToDo: Implement logic to save the Order and populated OrderItems
        System.Savepoint sp = Database.setSavepoint();
        try {
            if (null == orderRecord.Pricebook2Id) {
                orderRecord.Pricebook2Id = Constants.STANDARD_PRICEBOOK_ID;
            }
            upsert orderRecord;
            List<OrderItem> orderItemsToUpsert = new List<OrderItem>();
            List<OrderItem> orderItemsToDelete = new List<OrderItem>();
            for (OrderItem oi : orderItemList) {
                if (oi.Quantity > 0) {
                    if (null == oi.OrderId) {
                        oi.OrderId = orderRecord.Id;
                    }
                    orderItemsToUpsert.add(oi);
                } else if (oi.Id != null) {
                    orderItemsToDelete.add(oi);
                }
            }
            upsert orderItemsToUpsert;
            delete orderItemsToDelete;
        } catch (Exception e) {
            Database.rollback(sp);
            apexPages.addMessage(new ApexPages.message(ApexPages.Severity.INFO,Constants.ERROR_MESSAGE));
        }
    }
    /**
* @name First
* @description
**/
    public void First(){
        standardSetController.first();
        PopulateOrderItems();
    }
    /**
* @name Next
* @description
**/
    public void Next(){
        standardSetController.next();
        PopulateOrderItems();
    }
    
    
    /**
* @name Previous
* @description
**/
    public void Previous(){
        standardSetController.previous();
        PopulateOrderItems();
    }
    /**
* @name Last
* @description
**/
    public void Last(){
        standardSetController.last();
        PopulateOrderItems();
    }
    /**
* @name GetHasPrevious
* @description
**/
    public Boolean GetHasPrevious(){
        return standardSetController.getHasPrevious();
    }
    
    /**
* @name GetHasNext
* @description
**/
    public Boolean GetHasNext(){
        return standardSetController.getHasNext();
    }
    
    /**
* @name GetTotalPages
* @description
**/
    public Integer GetTotalPages(){
        return (Integer)Math.ceil(standardSetController.getResultSize() / (Decimal)Constants.DEFAULT_ROWS);
    }
    
    /**
* @name GetPageNumber
* @description
**/
    public Integer GetPageNumber(){
        return standardSetController.getPageNumber();
    }
    
    /**
* @name GetFamilyOptions
* @description
**/
    public List<SelectOption> GetFamilyOptions() {
        List<SelectOption> options = new List<SelectOption>{
            new SelectOption(Constants.SELECT_ONE, Constants.SELECT_ONE)
                };
                    
                    for (Schema.PicklistEntry ple : Constants.PRODUCT_FAMILY) {
                        options.add(new SelectOption(ple.getValue(), ple.getLabel()));
                    }
        return options;
    }
    
    /**
* @name QueryOrderRecord
* @description
**/
    public static Order QueryOrderRecord(Id orderId){
        return [
            SELECT Id, AccountId, EffectiveDate, Name, Status, Pricebook2Id,
            (
                SELECT Id, OrderId, Quantity, UnitPrice, PricebookEntryId, Product2Id,
                Product2.Name, Product2.Family, Product2.Quantity_Remaining__c
                FROM OrderItems
            )
            FROM Order
            WHERE Id = :orderId
        ];
    }
}

Hi,

Trailhead superbadge 7th challege on Adv apex specialist I m facing below error: Challenge Not yet complete... here's what's wrong:  Ensure that you've implemented the correct logic for the Save button. Please let me know how to resolve

Hi,

Trailhead superbadge 7th challege on Adv apex specialist I m facing below error: Challenge Not yet complete... here's what's wrong:  Ensure that you've implemented the correct logic for the Save button. Please let me know how to resolve