*
   * @throws IllegalArgumentException if the stream consists of two or more elements.
   * @throws NullPointerException if any element in the stream is {@code null}.
   * @return {@code Optional.of(onlyElement)} if the stream has exactly one element (must not be
   *     {@code null}) and returns {@code Optional.empty()} if it has none.
   */
  @SuppressWarnings("unchecked")

        assertNotNull(res);
        assertNotNull(res.getValue());
        assertTrue(Files.exists(res.getValue()));

        Node node = session.collectDependencies(session.createDependencyCoordinate(coord));
        assertNotNull(node);
        assertEquals(8, node.getChildren().size());
    }