code: public static void addInputContext(Job job, String inputName, String key, String value, int inputId) {
      // Check that this named output has been configured before
      Configuration conf = job.getConfiguration();
      // Add specific configuration
      conf.set(MI_PREFIX + inputName + "." + inputId + CONF + "." + key, value);
    }
docs: Specific (key, value) configurations for each Input. Some Input Formats
  read specific configuration values and act based on them.