Update weixin-java-pay/src/test/java/com/github/binarywang/wxpay/service/impl/MultiAppIdSwitchoverTest.java

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: binarywang

weixin-java-pay/src/test/java/com/github/binarywang/wxpay/service/impl/MultiAppIdSwitchoverTest.java

@@ -19,10 +19,10 @@
 public class MultiAppIdSwitchoverTest {
 
   private WxPayService payService;
-  private String testMchId = "1234567890";
-  private String testAppId1 = "wx1111111111111111";
-  private String testAppId2 = "wx2222222222222222";
-  private String testAppId3 = "wx3333333333333333";
+  private final String testMchId = "1234567890";
+  private final String testAppId1 = "wx1111111111111111";
+  private final String testAppId2 = "wx2222222222222222";
+  private final String testAppId3 = "wx3333333333333333";
 
   @BeforeMethod
   public void setup() {