Entry<Integer, String> entry2 = (Entry<Integer, String>) entries.toArray()[0];
    assertThrows(UnsupportedOperationException.class, () -> entry2.setValue("four"));
  }

  public void testImmutableEntry() {
    Entry<String, Integer> e = immutableEntry("foo", 1);
    assertThat(e.getKey()).isEqualTo("foo");
    assertEquals(1, (int) e.getValue());