* CharStreams} method returns a singleton writer whose {@code close} method has no effect, while
   * the {@link Writer#nullWriter()} method returns a new instance whose methods throw after the
   * instance is {@link Writer#close() closed}.
   *
   * @since 15.0
   */
  public static Writer nullWriter() {
    return NullWriter.INSTANCE;
  }

        }

        @Test
        @DisplayName("Should close pool with active transports")
        void testClosePoolWithActiveTransports() throws CIFSException {
            // Given
            when(transportPool.close()).thenReturn(true);

            // When
            boolean result = transportPool.close();

            // Then
            assertTrue(result);
            verify(transportPool).close();

            return invocation.getArgument(1);
        });

        // When: Create iterator and close multiple times
        NetServerEnumIterator iterator = new NetServerEnumIterator(parent, treeHandle, "*", 0, null);

        iterator.close();
        iterator.close(); // Second close should be safe

        // Then: Tree handle should be released only once
        verify(treeHandle, times(1)).release();

	}
	w := NewWriter(&buf)
	if _, err := w.CreateHeader(h); err != nil {
		t.Fatalf("unexpected CreateHeader error: %v", err)
	}
	if err := w.Close(); err != nil {
		t.Fatalf("unexpected Close error: %v", err)
	}

	want, err := os.ReadFile("testdata/time-go.zip")
	if err != nil {
		t.Fatalf("unexpected ReadFile error: %v", err)
	}

- `org.codelibs.curl.io.ContentCache` and `ContentOutputStream`: internal utilities for streaming and caching.

Refer to the Javadoc for full API details.

## Building and Testing

```bash
git clone https://github.com/codelibs/curl4j.git
cd curl4j
mvn clean test
```

## License

        }
    }

    @Test
    @DisplayName("EmptyIterator should handle close operations multiple times")
    void testMultipleCloseOperations() {
        // When & Then
        assertDoesNotThrow(() -> {
            try {
                emptyIterator.close();
                emptyIterator.close();
                emptyIterator.close();
            } catch (CIFSException e) {
                throw new RuntimeException(e);

    void testClose_True() throws CIFSException {
        // Test close() method when true
        when(mockDelegate.close()).thenReturn(true);
        assertTrue(cifsContextWrapper.close());
        verify(mockDelegate).close();
    }

    @Test
    void testClose_False() throws CIFSException {
        // Test close() method when false
        when(mockDelegate.close()).thenReturn(false);

import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

@GwtCompatible
@NullMarked
public class Helpers {
  // Clone of Objects.equals
  static boolean equal(@Nullable Object a, @Nullable Object b) {
    return a == b || (a != null && a.equals(b));
  }

  // Clone of Lists.newArrayList
  public static <E extends @Nullable Object> List<E> copyToList(Iterable<? extends E> elements) {

   * any exceptions thrown when attempting to close a closeable will be suppressed. Otherwise, the
   * <i>first</i> exception to be thrown from an attempt to close a closeable will be thrown and any
   * additional exceptions that are thrown after that will be suppressed.
   */
  @Override
  public void close() throws IOException {
    Throwable throwable = thrown;

    // close closeables in LIFO order
    while (!stack.isEmpty()) {

    logger.get().log(FINER, "cancelling {0}", this);
    boolean cancelled = future.cancel(mayInterruptIfRunning);
    if (cancelled) {
      close();
    }
    return cancelled;
  }

  private void close() {
    logger.get().log(FINER, "closing {0}", this);
    closeables.close();
  }

  private <U extends @Nullable Object> ClosingFuture<U> derive(FluentFuture<U> future) {