.tag(tag as Any)
        .build()
    assertThat(request.tag<Any>()).isSameAs(tag)
    assertThat(request.tag(Any::class)).isSameAs(tag)
    assertThat(request.tag(String::class)).isNull()

    // Alternate access APIs also work.
    assertThat(request.tag<Any>()).isSameAs(tag)
    assertThat(request.tag(Any::class)).isSameAs(tag)
  }

  @Test
  fun nullRemovesTag() {
    val request =