[COLLECTIONS-706] Set Entry count to 0 after remove.

src/changes/changes.xml

@@ -45,6 +45,9 @@
     <action issue="COLLECTIONS-706" dev="ggregory" type="fix" due-to="Richard Eckart de Castilho, Gary Gregory">
       Add SetUtils.unmodifiableSet(T... items) method.
     </action>
+    <action issue="COLLECTIONS-709" dev="ggregory" type="fix" due-to="Robert Wertman">
+      MultiSet.Entry::getCount() isn't 0 after removing the last element.
+    </action>
   </release>
   <release version="4.2" date="2018-07-11" description="Update from Java 6 to Java 7, bug fixes, and small changes.">
     <action issue="COLLECTIONS-681" dev="kinow" type="add" due-to="Stephan Fuhrmann">

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

@@ -265,6 +265,7 @@ public abstract class AbstractMapMultiSet<E> extends AbstractMultiSet<E> {
             } else {
                 map.remove(object);
                 size -= mut.value;
+                mut.value = 0;
             }
         }
         return oldCount;

src/test/java/org/apache/commons/collections4/multiset/AbstractMultiSetTest.java

@@ -462,6 +462,22 @@ public abstract class AbstractMultiSetTest<T> extends AbstractCollectionTest<T>
         assertEquals(false, it2.hasNext());
     }
 
+    @SuppressWarnings("unchecked")
+    public void testMultiSetEntrySetUpdatedToZero() {
+        if (!isAddSupported()) {
+            return;
+        }
+        final MultiSet<T> multiset = makeObject();
+        multiset.add((T) "A");
+        multiset.add((T) "A");
+        final MultiSet.Entry<T> entry = multiset.entrySet().iterator().next();
+        assertEquals(2, entry.getCount());
+        multiset.remove((T) "A");
+        assertEquals(1, entry.getCount());
+        multiset.remove((T) "A");
+        assertEquals(0, entry.getCount());
+    }
+
     @SuppressWarnings("unchecked")
     public void testMultiSetToArray() {
         if (!isAddSupported()) {