src/share/classes/java/util/HashMap.java

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*** 1210,1219 ****
--- 1210,1221 ----
      }
  
      @Override
      public V merge(K key, V value,
                     BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
+         if (value == null)
+             throw new NullPointerException();
          if (remappingFunction == null)
              throw new NullPointerException();
          int hash = hash(key);
          Node<K,V>[] tab; Node<K,V> first; int n, i;
          int binCount = 0;