// ## Assert ##
        assertEquals(before, after);
    }

    private long countTmpFiles() {
        return Arrays.stream(Objects.requireNonNull(Curl.tmpDir.listFiles())).map(File::getName)
                .filter(s -> s.startsWith(PREFIX) && s.endsWith(SUFFIX)).count();
    }

    }

    public void setHeaders(final Map<String, List<String>> headers) {
        if (headers != null) {
            final Map<String, List<String>> map = new HashMap<>();
            headers.entrySet().stream().filter(e -> e.getKey() != null)
                    .forEach(e -> map.put(e.getKey().toLowerCase(Locale.ROOT), e.getValue()));
            this.headers = map;
        }
    }