h ^= fingerprint(buf, bufLen);
      h = remix(h);
      buf[bufLen++] = getChar(h);

      int x0 = buf[bufLen - 1] & 0xff;
      int x1 = buf[bufLen - 2] & 0xff;
      int x2 = buf[bufLen - 3] & 0xff;
      int x3 = buf[bufLen / 2] & 0xff;
      buf[((x0 << 16) + (x1 << 8) + x2) % bufLen] ^= x3;
      buf[((x1 << 16) + (x2 << 8) + x3) % bufLen] ^= i % 256;
    }

      h ^= fingerprint(buf, bufLen);
      h = remix(h);
      buf[bufLen++] = getChar(h);

      int x0 = buf[bufLen - 1] & 0xff;
      int x1 = buf[bufLen - 2] & 0xff;
      int x2 = buf[bufLen - 3] & 0xff;
      int x3 = buf[bufLen / 2] & 0xff;
      buf[((x0 << 16) + (x1 << 8) + x2) % bufLen] ^= x3;
      buf[((x1 << 16) + (x2 << 8) + x3) % bufLen] ^= i % 256;
    }

    /** Case 2: Key conflict (without .overwrite) → Overwrite with value from responseDataMap */
    public void test_mergeResponseData_keyConflict() {
        Map<String, Object> dataMap = new HashMap<>();
        dataMap.put("x", "X0");
        Map<String, Object> responseDataMap = new HashMap<>();
        responseDataMap.put("x", "X1");

        indexUpdateCallback.mergeResponseData(dataMap, responseDataMap);

        assertEquals(1, dataMap.size());