code: public JSONCompareResult fail(String field, Object expected, Object actual) {
          _fieldFailures.add(new FieldComparisonFailure(field, expected, actual));
          this._field = field;
          this._expected = expected;
          this._actual = actual;
          fail(formatFailureMessage(field, expected, actual));
          return this;
      }
docs: Identify that the comparison failed
  @param field Which field failed
  @param expected Expected result
  @param actual Actual result
  @return result of comparision