--- old/src/share/classes/java/util/Map.java	2013-10-03 20:30:26.863126340 -0700
+++ new/src/share/classes/java/util/Map.java	2013-10-03 20:30:26.707126333 -0700
@@ -577,6 +577,7 @@
     * @throws NullPointerException if the specified key is null and this map
     * does not permit null keys
     * (<a href="Collection.html#optional-restrictions">optional</a>)
+    * @since 1.8
     */
     default V getOrDefault(Object key, V defaultValue) {
         V v;
@@ -1198,6 +1199,9 @@
                 oldValue = get(key);
             } else {
                 if (value == null) {
+                    if((oldValue = remove(key)) != null) {
+                        throw new ConcurrentModificationException("non-null value");
+                    }
                     return null;
                 }