code: protected final int parseIndex(String indexString) {
          try {
              return Integer.parseInt(indexString);
          } catch(Exception e) {
              String msg = "Error converting \"" + indexString + "\" into an integer.  Cause: " + e;
              LOGGER.error(msg, e);
              throw new RuntimeException(msg, e);
          }
      }
docs: Attempt to convert a String indexString into an integer index.
  @param indexString the index string
  @return the converted integer