#2249 - Bug with DbJson Jackson property that is null is updated as null (unnecessarily included in update)

When the value is null and not changed then is was null before and should not be treated as dirty. Hence only check for dirty when value != null in BeanDescriptor 3182

ebean-core/src/test/java/org/tests/json/TestDbJson_Jackson3.java

@@ -74,6 +74,6 @@ public class TestDbJson_Jackson3 extends BaseTestCase {
 
     final List<String> sql = LoggedSql.stop();
     assertThat(sql).hasSize(1);
-    assertThat(sql.get(0)).contains("update ebasic_json_list set name=?, beans=?, bean_list=?, plain_bean=?, version=? where id=?");
+    assertThat(sql.get(0)).contains("update ebasic_json_list set name=?, bean_list=?, plain_bean=?, version=? where id=?");
   }
 }