* Creates a thumbnail generation task for the specified document.
     *
     * @param path the file path or URL of the document
     * @param docMap the document metadata map containing field values
     * @return a tuple containing the generator name, thumbnail ID, and path
     */
    @Override
    public Tuple3<String, String, String> createTask(final String path, final Map<String, Object> docMap) {

                return null;
            }

            Object mimeType = docMap.get("mimetype");
            if (mimeType == null) {
                return null;
            }

            // Create a task tuple
            return new Tuple3<>("task-id", path, mimeType.toString());
        }
    }

   *
   * {@snippet :
   * for (B b0 : sets.get(0)) {
   *   for (B b1 : sets.get(1)) {
   *     ...
   *     ImmutableList<B> tuple = ImmutableList.of(b0, b1, ...);
   *     // operate on tuple
   *   }
   * }
   * }
   *
   * <p>Note that if any input set is empty, the Cartesian product will also be empty. If no sets at