for (int i = 0; i < num; i++) {
        rest[i] = partsArray[i + 2];
      }

      assertEquals(expected, joiner.join(partsArray[0], partsArray[1], rest));

      StringBuilder sb3 = new StringBuilder().append('x');
      joiner.appendTo(sb3, partsArray[0], partsArray[1], rest);
      assertEquals("x" + expected, sb3.toString());
    }
  }

  public void test_useForNull_skipNulls() {