final Path path = Paths.get(logFilePath, filename);
            return asStream(filename).contentTypeOctetStream().stream(out -> {
                try (InputStream in = Files.newInputStream(path)) {
                    out.write(in);
                }
            });
        }
        throwValidationError(messages -> messages.addErrorsCouldNotFindLogFile(GLOBAL, filename), this::asIndexHtml);