Use LinkedHashSet for deterministic iterations (#2918)

apollo-configservice/src/test/java/com/ctrip/framework/apollo/configservice/service/ReleaseMessageServiceWithCacheTest.java

@@ -94,13 +94,15 @@ public class ReleaseMessageServiceWithCacheTest {
 
     List<ReleaseMessage> latestReleaseMsgGroupByMsgContent =
         releaseMessageServiceWithCache
-            .findLatestReleaseMessagesGroupByMessages(Sets.newHashSet(someMsgContent, anotherMsgContent));
+            .findLatestReleaseMessagesGroupByMessages(Sets.newLinkedHashSet(
+                    Arrays.asList(someMsgContent, anotherMsgContent))
+            );
 
     assertEquals(2, latestReleaseMsgGroupByMsgContent.size());
-    assertEquals(1, latestReleaseMsgGroupByMsgContent.get(1).getId());
-    assertEquals(someMsgContent, latestReleaseMsgGroupByMsgContent.get(1).getMessage());
-    assertEquals(3, latestReleaseMsgGroupByMsgContent.get(0).getId());
-    assertEquals(anotherMsgContent, latestReleaseMsgGroupByMsgContent.get(0).getMessage());
+    assertEquals(3, latestReleaseMsgGroupByMsgContent.get(1).getId());
+    assertEquals(anotherMsgContent, latestReleaseMsgGroupByMsgContent.get(1).getMessage());
+    assertEquals(1, latestReleaseMsgGroupByMsgContent.get(0).getId());
+    assertEquals(someMsgContent, latestReleaseMsgGroupByMsgContent.get(0).getMessage());
 
   }