COLLECTIONS-660: uncomment and change order of assertEquals

src/test/java/org/apache/commons/collections4/map/AbstractMapTest.java

@@ -1956,19 +1956,13 @@ public abstract class AbstractMapTest<K, V> extends AbstractObjectTest {
         assertEquals("Map should be same size as HashMap", size, getMap().size());
         assertEquals("Map should be empty if HashMap is", empty, getMap().isEmpty());
         assertEquals("hashCodes should be the same", getConfirmed().hashCode(), getMap().hashCode());
-        // this fails for LRUMap because confirmed.equals() somehow modifies
-        // map, causing concurrent modification exceptions.
-        // assertEquals("Map should still equal HashMap", confirmed, map);
-        // this works though and performs the same verification:
+        // changing the order of the assertion below fails for LRUMap because confirmed is
+        // another collection (e.g. treemap) and confirmed.equals() creates a normal iterator (not
+        // #mapIterator()), which modifies the parent expected modCount of the map object, causing
+        // concurrent modification exceptions.
+        // Because of this we have assertEquals(map, confirmed), and not the other way around.
+        assertEquals("Map should still equal HashMap", map, confirmed);
         assertTrue("Map should still equal HashMap", getMap().equals(getConfirmed()));
-        // TODO: this should really be reexamined to figure out why LRU map
-        // behaves like it does (the equals shouldn't modify since all accesses
-        // by the confirmed collection should be through an iterator, thus not
-        // causing LRUMap to change).
-        // When comparing two maps, the entries in the map have to be accessed
-        // (usually with the get(Object) method). In the case of the LRUMap, this
-        // also alters the modCount as moveToMRU is called for the retrieved entry.
-        // Imho, the modCount should not be increased for a read-only operation.
     }
 
     public void verifyEntrySet() {