/**
     * Creates a CoordinatorHelper that captures request bodies sent via CurlHelper.
     * The mock CurlHelper records the last request path and body for assertion.
     */
    private CoordinatorHelper createCapturingHelper(final String testInstanceId, final AtomicReference<String> capturedPath,
            final AtomicReference<String> capturedBody, final CurlResponse mockResponse) {
        final CurlHelper mockCurlHelper = new CurlHelper() {