reverted back to allow acquireUsing to be passsed a NULL value

src/test/java/net/openhft/chronicle/map/ChronicleMapTest.java

@@ -418,7 +418,7 @@ public class ChronicleMapTest {
         map.close();
     }
 
-    @Test(expected = IllegalArgumentException.class)
+    @Test
     public void testAcquireWithNullContainer() throws Exception {
         ChronicleMap<CharSequence, LongValue> map = getSharedMap(10 * 1000, 128, 24);
         map.acquireUsing("key", new LongValue$$Native());