// mongo specific options:
OptionSpec<String> host = parser.accepts("host", "MongoDB host").withRequiredArg().defaultsTo("127.0.0.1");
OptionSpec<Integer> port = parser.accepts("port", "MongoDB port").withRequiredArg().ofType(Integer.class).defaultsTo(27017);
OptionSpec<String> dbName = parser.accepts("db", "MongoDB database").withRequiredArg();
OptionSpec<Integer> clusterIds = parser.accepts("clusterIds", "Cluster Ids").withOptionalArg().ofType(Integer.class).withValuesSeparatedBy(',');
OptionSpec<String> nonOption = parser.nonOptions();
OptionSpec<?> help = parser.acceptsAll(asList("h", "?", "help"), "show help").forHelp();
OptionSet options = parser.parse(args);
if (options.has(help)) {
parser.printHelpOn(System.out);