fixing a compiler warning

Author: cowtowncoder

afterburner/src/test/java/com/fasterxml/jackson/module/afterburner/ser/NullSerializationTest.java

@@ -74,8 +74,8 @@ static class BeanWithNullProps
     /**********************************************************
      */
 
-    private final ObjectMapper MAPPER = mapperWithModule();
-    
+    private final ObjectMapper MAPPER = newObjectMapper();
+
     public void testSimple() throws Exception
     {
         assertEquals("null", MAPPER.writeValueAsString(null));