Fix size calculation of entrySet in MultiSet.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/collections/trunk@1714707 13f79535-47bb-0310-9956-ffa450edef68

src/main/java/org/apache/commons/collections4/multiset/AbstractMapMultiSet.java

@@ -558,7 +558,7 @@ public abstract class AbstractMapMultiSet<E> extends AbstractCollection<E> imple
 
         @Override
         public int size() {
-            return parent.entrySet.size();
+            return parent.map.entrySet().size();
         }
 
         @Override