code: public Stream maxBy(String inputFieldName) {
          Aggregator<ComparisonAggregator.State> max = new Max(inputFieldName);
          return comparableAggregateStream(inputFieldName, max);
      }
docs: This aggregator operation computes the maximum of tuples by the given {@code inputFieldName} and it is
  assumed that its value is an instance of {@code Comparable}. If the value of tuple with field {@code inputFieldName} is not an
  instance of {@code Comparable} then it throws {@code ClassCastException}
  
  @param inputFieldName input field name
  @return the new stream with this operation.