HBASE-23983 Fixed Spotbugs complaint in RegionStates related to ignored return value

Signed-off-by: Duo Zhang <zhangduo@apache.org>

Author: HorizonNet

hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/RegionStates.java

@@ -126,7 +126,11 @@ RegionStateNode createRegionStateNode(RegionInfo regionInfo) {
     synchronized (regionsMapLock) {
       RegionStateNode node = regionsMap.computeIfAbsent(regionInfo.getRegionName(),
         key -> new RegionStateNode(regionInfo, regionInTransition));
-      encodedRegionsMap.putIfAbsent(regionInfo.getEncodedName(), node);
+
+      if (encodedRegionsMap.get(regionInfo.getEncodedName()) != node) {
+        encodedRegionsMap.put(regionInfo.getEncodedName(), node);
+      }
+
       return node;
     }
   }