code: public static void assertJsonPartNotEquals(Object expected, Object fullJson, String path, Configuration configuration) {
          Diff diff = create(expected, fullJson, FULL_JSON, path, configuration);
          if (diff.similar()) {
              if (ROOT.equals(path)) {
                  doFail("Expected different values but the values were equal.");
              } else {
                  doFail(String.format("Expected different values in node \"%s\" but the values were equal.", path));
              }
          }
      }
docs: Compares part of the JSON and fails if they are equal.
  Path has this format "root.array[0].value".