public void test_append_stringWithBackslash() {
        StringBuilder buf = new StringBuilder();
        Supplier<Object> supplier = () -> "path\\to\\file";

        monitorTarget.append(buf, "pathKey", supplier);
        assertEquals("\"pathKey\":\"path\\\\to\\\\file\"", buf.toString());
    }

    // Test append method with exception in supplier
    public void test_append_exceptionInSupplier() {