code: public static String javaOptStringFromAzkabanProps(Props props, String key) {
      String value = props.get(key);
      if (value == null) {
        throw new RuntimeException(String.format("Cannot find property [%s], in azkaban props: [%s]",
            key, value));
      }
      return String.format("-D%s=%s", key, value);
    }
docs: <pre>
  constructions a javaOpts string based on the Props, and the key given, will return
  String.format("-D%s=%s", key, value);
  </pre>
  
  @return will return String.format("-D%s=%s", key, value). Throws RuntimeException if props not
  present