code: public ResultMatcher isNotEqualTo(final Object expected) {
          return new AbstractResultMatcher(path, configuration) {
              public void doMatch(Object actual) {
                  Diff diff = createDiff(expected, actual);
                  if (diff.similar()) {
                      failWithMessage("JSON is equal.");
                  }
              }
          };
      }
docs: Fails if compared documents are equal. The expected object is converted to JSON
  before comparison. Ignores order of sibling nodes and whitespaces.