fix #2092. (#2648)

* fix #2092.

* Revert "fix #2092."

This reverts commit d8076ef2

* fix #2092. change deferredResults key toLowerCase.

* change HashMap to TreeMap.

* add DeferredResultWrapper compareTo;

apollo-configservice/src/main/java/com/ctrip/framework/apollo/configservice/controller/NotificationControllerV2.java

@@ -21,7 +21,9 @@ import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
 import com.google.common.collect.Multimap;
 import com.google.common.collect.Multimaps;
+import com.google.common.collect.Ordering;
 import com.google.common.collect.Sets;
+import com.google.common.collect.TreeMultimap;
 import com.google.gson.Gson;
 import com.google.gson.reflect.TypeToken;
 import org.slf4j.Logger;
@@ -54,7 +56,7 @@ import java.util.function.Function;
 public class NotificationControllerV2 implements ReleaseMessageListener {
   private static final Logger logger = LoggerFactory.getLogger(NotificationControllerV2.class);
   private final Multimap<String, DeferredResultWrapper> deferredResults =
-      Multimaps.synchronizedSetMultimap(HashMultimap.create());
+      Multimaps.synchronizedSetMultimap(TreeMultimap.create(String.CASE_INSENSITIVE_ORDER, Ordering.natural()));
   private static final Splitter STRING_SPLITTER =
       Splitter.on(ConfigConsts.CLUSTER_NAMESPACE_SEPARATOR).omitEmptyStrings();
   private static final Type notificationsTypeReference =

apollo-configservice/src/main/java/com/ctrip/framework/apollo/configservice/wrapper/DeferredResultWrapper.java

@@ -7,6 +7,7 @@ import com.ctrip.framework.apollo.core.dto.ApolloConfigNotification;
 
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
+import org.springframework.lang.NonNull;
 import org.springframework.web.context.request.async.DeferredResult;
 
 import java.util.List;
@@ -15,7 +16,7 @@ import java.util.Map;
 /**
  * @author Jason Song(song_s@ctrip.com)
  */
-public class DeferredResultWrapper {
+public class DeferredResultWrapper implements Comparable<DeferredResultWrapper> {
   private static final ResponseEntity<List<ApolloConfigNotification>>
       NOT_MODIFIED_RESPONSE_LIST = new ResponseEntity<>(HttpStatus.NOT_MODIFIED);
 
@@ -64,4 +65,9 @@ public class DeferredResultWrapper {
   public DeferredResult<ResponseEntity<List<ApolloConfigNotification>>> getResult() {
     return result;
   }
+
+  @Override
+  public int compareTo(@NonNull DeferredResultWrapper deferredResultWrapper) {
+    return this == deferredResultWrapper ? 0 : 1;
+  }
 }