public boolean isDefined(final Argument arg) {
    final List<String[]> result = values.get(arg);
    return (result != null);
  }
Returns whetheror not the command line argument was actually provided on the command line.

@param arg argument to query
@return true if the argument is defined by the command line, false otherwise
extensions/geode-modules-session/src/main/java/org/apache/geode/modules/session/installer/args/ArgumentValues.java