public class QuoteSyncUtil {

public static boolean isRunningTest = false;

private static Map<String, String> quoteFieldMap = new Map<String, String>();
private static Map<String, String> quoteLineFieldMap = new Map<String, String>();

static {
public static String getQuoteFieldsString() {
    String fields = '';
    for (String field : getQuoteFields()) {
        fields += ', ' + field;
    }
    return fields;
}
    Map<String, QuoteLineSyncField__c> quoteLineFields = QuoteLineSyncField__c.getAll();
    system.debug('KENNY '+quoteLineFields);

    for (String quoteLineField : quoteLineFields.keySet()) {
        QuoteLineSyncField__c quoteLineSyncField = QuoteLineSyncField__c.getInstance(quoteLineField);
        //FIXME - uppercase value cause NPE
        quoteLineFieldMap.put(quoteLineSyncField.Name, quoteLineSyncField.OppLineSyncField__c);
        system.debug('KENNY '+QuoteLineSyncField__c.getInstance(quoteLineField));
        //quoteLineFieldMap.put(quoteLineField, quoteLineSyncField.OppLineSyncField__c);

    if(quotelinefield == 'Product_Type__c'){
        System.debug('********* ' + quoteLineField);
        System.debug('^^^^^^^^^ ' + quotelineSyncField.OppLineSyncField__c);
        }
    }
}

public static Set<String> getQuoteLineFields() {
    system.debug('KENNY '+quoteLineFieldMap.keyset());
    return quoteLineFieldMap.keySet();
}

List<String> oppLineFields = QuoteSyncUtil.getOppLineFields();

// pricebook entry ids in trigger
Set<Id> pbEntryIds = new Set<Id>();

// a Set of Pricebook2 Ids represented in Trigger.new
Set<Id> setPricebookId = new Set<Id>();

String oliFields = QuoteSyncUtil.getOppLineFieldsString();
String qliFields =  QuoteSyncUtil.getQuoteLineFieldsString();

String qliIds = '';
String quoteIdString = '';
for (QuoteLineItem qli : qlisInTrigger) {
    if (qliIds != '') qliIds += ', ';
    qliIds += ''' + qli.Id + ''';

    if (quoteIdString != '') quoteIdString += ', ';
    quoteIdString += ''' + qli.QuoteId + ''';

    pbEntryIds.add(qli.PricebookEntryId);
}

String qliQuery = 'SELECT Id, ' +
                    'QuoteId, ' +
                     'PricebookEntryId, ' +
                     'UnitPrice, ' +
                     'Quantity, ' +
                     'Discount, ' +
                     'ServiceDate, ' +
                     'SortOrder, ' +
                     'PricebookEntry.Product2.Name, ' +
                     'PricebookEntry.Product2.Product_Type__c, ' +
                     'PricebookEntry.Product2.Approval_Required__c, ' +
                     'PricebookEntry.Pricebook2Id, ' +
                     'ListPrice, ' +
                     'Discount_off_List__c ' +
                     qliFields +
                     ' FROM QuoteLineItem where QuoteId in (' + quoteIdString + ')';

System.debug(qliQuery);