Add testcase to assert Null fields serialization without JSONParserConfiguration

Author: harshith8854

src/test/java/org/json/junit/JSONObjectTest.java

@@ -4025,9 +4025,23 @@ public void jsonObjectParseNullFieldsWithParserConfiguration() {
         JSONParserConfiguration jsonParserConfiguration = new JSONParserConfiguration();
         RecursiveBean bean = new RecursiveBean(null);
         JSONObject jsonObject = new JSONObject(bean, jsonParserConfiguration.withUseNativeNulls(true));
-        String textStr = jsonObject.toString();
-        assertTrue("name(uninitialized field) should be serialized", textStr.contains("\"name\""));
-        assertTrue("ref(uninitialized field) should be serialized", textStr.contains("\"ref\""));
-        assertTrue("ref2(uninitialized field) should be serialized", textStr.contains("\"ref2\""));
+        assertTrue("name key should be present", jsonObject.has("name"));
+        assertTrue("ref key should be present", jsonObject.has("ref"));
+        assertTrue("ref2 key should be present", jsonObject.has("ref2"));
     }
+
+    /**
+     * Tests the behavior of the {@link JSONObject} when parsing a bean with null fields
+     * without using a custom {@link JSONParserConfiguration}.
+     * 
+     * <p>This test ensures that uninitialized fields in the bean are not serialized
+     * into the resulting JSON object, and the object remains empty.</p>
+     */
+    @Test
+    public void jsonObjectParseNullFieldsWithoutParserConfiguration() {
+        RecursiveBean bean = new RecursiveBean(null);
+        JSONObject jsonObject = new JSONObject(bean);
+        assertTrue("JSONObject should be empty", jsonObject.isEmpty());
+    }
+
 }