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

*** 1135,1146 ****
       * 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
--- 1135,1144 ----
*** 1168,1192 ****
       */
      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) {
                  remove(key);
-                 return null;
              } else {
!                 put(key, value);
!                 return value;
!             }
          }
      }
  }
--- 1166,1180 ----
       */
      default V merge(K key, V value,
              BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
          Objects.requireNonNull(remappingFunction);
          V oldValue = get(key);
!         V newValue = (oldValue == null) ? value :
!                    remappingFunction.apply(oldValue, value);
!         if(newValue == null) {
              remove(key);
          } else {
!             put(key, newValue);
          }
+         return newValue;
      }
  }