assertEquals(1, dataMap.size());
        assertEquals("X1", dataMap.get("x"));
    }

    /** Case 3: Only overwrite key (baseKey not set) → generate baseKey, remove overwrite key */
    public void test_mergeResponseData_overwriteOnly() {
        Map<String, Object> dataMap = new HashMap<>();
        Map<String, Object> responseDataMap = new HashMap<>();
        responseDataMap.put("y.overwrite", "Y1");