directExecutor());
    } else {
      switch (state.get()) {
        case SUBSUMED:
          throw new IllegalStateException(
              "Cannot call finishToFuture() after deriving another step");

        case WILL_CREATE_VALUE_AND_CLOSER:
          throw new IllegalStateException(
              "Cannot call finishToFuture() after calling finishToValueAndCloser()");

        case WILL_CLOSE:

    val call = client.newCall(request)
    val response = call.execute()
    response.body.close()
    assertFailsWith<IllegalStateException> {
      call.execute()
    }.also { expected ->
      assertThat(expected.message).isEqualTo("Already Executed")
    }
    assertFailsWith<IllegalStateException> {
      call.enqueue(callback)
    }.also { expected ->
      assertThat(expected.message).isEqualTo("Already Executed")

        .build(),
    )
    val response1 = get(server.url("/"))
    val source = response1.body.source()
    assertThat(source.readUtf8(5)).isEqualTo("ABCDE")
    source.close()
    assertFailsWith<IllegalStateException> {
      source.readByte()
    }
    assertThat(cache.writeAbortCount()).isEqualTo(1)
    assertThat(cache.writeSuccessCount()).isEqualTo(0)
    val response2 = get(server.url("/"))

            },
        ),
      )
    assertThat(readAscii(response.body.byteStream(), Int.MAX_VALUE))
      .isEqualTo("abc")
    assertFailsWith<IllegalStateException> {
      sinkReference.get().flush()
    }
    assertFailsWith<IllegalStateException> {
      sinkReference.get().write("ghi".toByteArray())
      sinkReference.get().emit()
    }
  }

  @Test
  fun getHeadersThrows() {

   * {@link java.util.stream.Collectors#toMap(java.util.function.Function,
   * java.util.function.Function) Collectors.toMap(Function, Function)}, which throws an {@code
   * IllegalStateException}.)
   *
   * @since 33.2.0 (available since 21.0 in guava-jre)
   */
  @SuppressWarnings("Java7ApiChecker")
  @IgnoreJRERequirement // Users will use this only if they're already using streams.

   * {@link java.util.stream.Collectors#toMap(java.util.function.Function,
   * java.util.function.Function) Collectors.toMap(Function, Function)}, which throws an {@code
   * IllegalStateException}.)
   *
   * @since 21.0
   */
  public static <T extends @Nullable Object, K extends Enum<K>, V>
      Collector<T, ?, ImmutableMap<K, V>> toImmutableEnumMap(