assertThat(atomicTags.computeIfAbsent(String::class) { "a" }).isEqualTo("a")
    assertThat(atomicTags.get()[String::class]).isEqualTo("a")
  }

  @Test
  fun computeIfAbsentWhenPresent() {
    val tags = EmptyTags.plus(String::class, "a")
    val atomicTags = AtomicReference(tags)
    assertThat(atomicTags.computeIfAbsent(String::class) { "b" }).isEqualTo("a")