code: private void handleArgBuildFile(final Deque<String> args) {
          final String value = args.pop();
          if (value == null) {
              throw new BuildException("You must specify a buildfile when using the --buildfile argument");
          }
          buildFile = new File(value.replace('/', File.separatorChar));
      }
docs: Handle the --buildfile, --file, -f argument