code: private boolean unequalNotNull(Object expected, Object actual) {
          if ((XMLUnit.getIgnoreWhitespace() || XMLUnit.getNormalizeWhitespace())
              && expected instanceof String && actual instanceof String) {
              String expectedString = ((String) expected).trim();
              String actualString = ((String) actual).trim();
              if (XMLUnit.getNormalizeWhitespace()) {
                  expectedString = normalizeWhitespace(expectedString);
                  actualString = normalizeWhitespace(actualString);
              }
              return !expectedString.equals(actualString);
          }
          return !(expected.equals(actual));
      }
docs: Test two non-null values for inequality
  @param expected
  @param actual
  @return TRUE if the values are not equals() equal (taking whitespace
  into account if necessary)