public final void hasSize(int expectedSize) {
    checkArgument(expectedSize >= 0, "expectedSize(%s) must be >= 0", expectedSize);
    check("size()").that(checkNotNull(actual).size()).isEqualTo(expectedSize);
  }
@Test
  public void hasSize() {
    assertThat(ImmutableMultimap.of(1, 2, 3, 4)).hasSize(2);
  }