1. 增加退款查询 退款单号，订单有效时间

pay-java-fuiou/src/main/java/com/egzosn/pay/fuiou/api/FuiouPayService.java

@@ -378,7 +378,18 @@ public class FuiouPayService extends BasePayService {
 
     @Override
     public Map<String, Object> refundquery(String tradeNo, String outTradeNo) {
-        return null;
+        return Collections.emptyMap();
+    }
+
+    /**
+     * 查询退款
+     *
+     * @param refundOrder 退款订单单号信息
+     * @return 返回支付方查询退款后的结果
+     */
+    @Override
+    public Map<String, Object> refundquery(RefundOrder refundOrder) {
+        return Collections.emptyMap();
     }
 
 
@@ -390,7 +401,7 @@ public class FuiouPayService extends BasePayService {
      */
     @Override
     public Map<String, Object> downloadbill(Date billDate, String billType) {
-        return null;
+        return Collections.emptyMap();
     }
 
     /**
@@ -403,7 +414,7 @@ public class FuiouPayService extends BasePayService {
      */
     @Override
     public Map<String, Object> secondaryInterface(Object tradeNoOrBillDate, String outTradeNoBillType, TransactionType transactionType) {
-        return null;
+        return Collections.emptyMap();
     }