private Iterator<String> getDocumentIds(CommandLine cl) {
        // Fetch document ids from stdin if no ids are passed in as command line arguments
        List<String> documentIds = List.of(cl.getArgs());
        // WARNING: CommandLine.getArgs may return a single empty string as the only element
        if (documentIds.isEmpty() ||
                documentIds.size() == 1 && documentIds.get(0).isEmpty()) {
            return new Scanner(stdIn);
        } else {
            return documentIds.iterator();
        }
    }
This class is responsible for parsing the command line arguments and print the help page.

@author bjorncs
vespaclient-java/src/main/java/com/yahoo/vespaget/CommandLineOptions.java