src/share/classes/java/util/Map.java

rev 8834 : 8029055: Map.merge and ConcurrentMap.merge @implSpec is not correct in case of non-existing key-value pair or a null value entry
Reviewed-by: duke

@@ -1135,12 +1135,10 @@
      * V oldValue = map.get(key);
      * V newValue = (oldValue == null) ? value :
      *              remappingFunction.apply(oldValue, value);
      * if (newValue == null)
      *     map.remove(key);
-     * else if (oldValue == null)
-     *     map.remove(key);
      * else
      *     map.put(key, newValue);
      * }</pre>
      *
      * <p>The default implementation makes no guarantees about synchronization

@@ -1168,25 +1166,15 @@
      */
     default V merge(K key, V value,
             BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
         Objects.requireNonNull(remappingFunction);
         V oldValue = get(key);
-        if (oldValue != null) {
-            V newValue = remappingFunction.apply(oldValue, value);
-            if (newValue != null) {
-                put(key, newValue);
-                return newValue;
-            } else {
-                remove(key);
-                return null;
-            }
-        } else {
-            if (value == null) {
+        V newValue = (oldValue == null) ? value :
+                   remappingFunction.apply(oldValue, value);
+        if(newValue == null) {
                 remove(key);
-                return null;
             } else {
-                put(key, value);
-                return value;
-            }
+            put(key, newValue);
         }
+        return newValue;
     }
 }