checkNotClosed();
    target.append(charSeq, start, end);
    return this;
  }

  private void checkNotClosed() throws IOException {
    if (closed) {
      throw new IOException("Cannot write to a closed writer.");
    }
  }

    assertEquals(Integer.MAX_VALUE, ms.headMultiset("b", CLOSED).size());
    assertEquals(Integer.MAX_VALUE, ms.headMultiset("a", CLOSED).size());

    assertEquals(3, ms.tailMultiset("c", CLOSED).size());
    assertEquals(Integer.MAX_VALUE, ms.tailMultiset("b", CLOSED).size());
    assertEquals(Integer.MAX_VALUE, ms.tailMultiset("a", CLOSED).size());
  }

  @J2ktIncompatible

    assertEquals(STRING, sink.getString());
  }

  public void testWriteFromStream_doesNotCloseThatStream() throws IOException {
    TestReader in = new TestReader();
    assertFalse(in.closed());
    sink.writeFrom(in);
    assertFalse(in.closed());
  }

  public void testWriteLines_withSpecificSeparator() throws IOException {
    sink.writeLines(ImmutableList.of("foo", "bar", "baz"), "\n");

        assertFalse(auth.isClosed());

        // Close the authenticator
        auth.close();

        // Verify it's closed
        assertTrue(auth.isClosed());
        // Cannot check password after closing as it now throws IllegalStateException
        // This is actually good security practice - closed authenticators cannot be accessed

        // Verify multiple closes don't cause issues

          ?: throw ProtocolException("expected the Content-Type to have a boundary parameter"),
    )

    @Throws(IOException::class)
    fun nextPart(): Part? {
      check(!closed) { "closed" }

      if (noMoreParts) return null

      // Read a boundary, skipping the remainder of the preceding part as necessary.
      if (partCount == 0 && source.rangeEquals(0L, dashDashBoundary)) {

    check(!closed) { "cache is closed" }
  }

  /** Force buffered operations to the filesystem. */
  @Synchronized
  @Throws(IOException::class)
  override fun flush() {
    if (!initialized) return

    checkNotClosed()
    trimToSize()
    journalWriter!!.flush()
  }

  @Synchronized fun isClosed(): Boolean = closed

      return multiset().subMultiset(fromElement, CLOSED, toElement, OPEN).elementSet();
    }

    @Override
    public SortedSet<E> headSet(@ParametricNullness E toElement) {
      return multiset().headMultiset(toElement, OPEN).elementSet();
    }

    @Override
    public SortedSet<E> tailSet(@ParametricNullness E fromElement) {
      return multiset().tailMultiset(fromElement, CLOSED).elementSet();
    }

    @Override

  }

  public void testWriteFromStream_doesNotCloseThatStream() throws IOException {
    TestInputStream in = new TestInputStream(new ByteArrayInputStream(new byte[10]));
    assertFalse(in.closed());
    sink.writeFrom(in);
    assertFalse(in.closed());
  }

  public void testClosesOnErrors_copyingFromByteSourceThatThrows() {
    for (TestOption option : EnumSet.of(OPEN_THROWS, READ_THROWS, CLOSE_THROWS)) {

  @Throws(IOException::class)
  fun processNextFrame() {
    check(!closed) { "closed" }

    readHeader()
    if (isControlFrame) {
      readControlFrame()
    } else {
      readMessageFrame()
    }
  }

  @Throws(IOException::class, ProtocolException::class)
  private fun readHeader() {
    if (receivedCloseFrame) throw IOException("closed")

    // Disable the timeout to read the first byte of a new frame.

import java.nio.charset.Charset;

/**
 * A destination to which bytes can be written, such as a file. Unlike an {@link OutputStream}, a
 * {@code ByteSink} is not an open, stateful stream that can be written to and closed. Instead, it
 * is an immutable <i>supplier</i> of {@code OutputStream} instances.
 *
 * <p>{@code ByteSink} provides two kinds of methods:
 *
 * <ul>