public String getComponent(int position) {
      if (position > components.size()) {
        return null;
      } else {
        return components.get(position - 1);
      }
    }
Get the component at the specified location.
Uses the range 1-n to match the notation used in the rule.

@param position position of the component in the range 1-n
@return the component at the specified location or null
ambari-server/src/main/java/org/apache/ambari/server/controller/AuthToLocalBuilder.java