code: @Override
      public DiffBuilder withDifferenceListeners(final ComparisonListener... comparisonListeners) {
          this.differenceListeners.addAll(Arrays.asList(comparisonListeners));
          return this;
      }
docs: Registers listeners that are notified of each comparison with
  outcome other than {@link ComparisonResult#EQUAL}.
  
  @see org.xmlunit.diff.DifferenceEngine#addDifferenceListener(ComparisonListener)