code: @SuppressWarnings({"unchecked"})
    public OutputCollector getCollector(String namedOutput, Reporter reporter)
      throws IOException {
      return getCollector(namedOutput, null, reporter);
    }
docs: Gets the output collector for a named output.
  <p/>
  
  @param namedOutput the named output name
  @param reporter    the reporter
  @return the output collector for the given named output
  @throws IOException thrown if output collector could not be created