out := make(chan string)
	go fibber(c, out, 0)
	go fibber(c, out, 1)
	for i := 0; i < 200; i++ {
		println(<-out)
	}

public class Slf4jMavenTransferListener extends AbstractTransferListener {

    protected final Logger out;

    public Slf4jMavenTransferListener() {
        this.out = LoggerFactory.getLogger(Slf4jMavenTransferListener.class);
    }

    // TODO should we deprecate?
    public Slf4jMavenTransferListener(Logger out) {
        this.out = out;
    }

    @Override
    public void transferInitiated(TransferEvent event) {

            System.out.println("=== REPOSITORY LEAKAGE TEST RESULTS ===");
            System.out.println(
                    "Repositories in shared request after building child2: " + repositoriesAfterChild2.size());
            repositoriesAfterChild2.forEach(
                    repo -> System.out.println("  - " + repo.getId() + " (" + repo.getUrl() + ")"));

            System.out.println("Child1 project repositories:");

        if (done) {
          System.out.println("completed");
        } else {
          if (firstUpdate) {
            firstUpdate = false;
            if (contentLength == -1) {
              System.out.println("content-length: unknown");
            } else {
              System.out.format("content-length: %d\n", contentLength);
            }
          }

          System.out.println(bytesRead);

          response2Body = response2.body().string();
          System.out.println("Response 2 response:          " + response2);
          System.out.println("Response 2 cache response:    " + response2.cacheResponse());
          System.out.println("Response 2 network response:  " + response2.networkResponse());
        }

        System.out.println("Response 2 equals Response 1? " + response1Body.equals(response2Body));
      }

        if (done) {
          System.out.println("completed");
        } else {
          if (firstUpdate) {
            firstUpdate = false;
            if (contentLength == -1) {
              System.out.println("content-length: unknown");
            } else {
              System.out.format("content-length: %d\n", contentLength);
            }
          }

          System.out.println(bytesWritten);

    // Schedule a job to cancel the call in 1 second.
    executor.schedule(() -> {
      System.out.printf("%.2f Canceling call.%n", (System.nanoTime() - startNanos) / 1e9f);
      call.cancel();
      System.out.printf("%.2f Canceled call.%n", (System.nanoTime() - startNanos) / 1e9f);
    }, 1, TimeUnit.SECONDS);

    System.out.printf("%.2f Executing call.%n", (System.nanoTime() - startNanos) / 1e9f);

        String destDir = "";
        if (args.length > 3) {
            destDir = args[3];
        }

        System.out.format("=> stylesheet %s%n", stylesheet);
        System.out.format("=> source %s%n", source);
        System.out.format("=> dest %s%n", dest);
        System.out.format("=> destDir %s%n", destDir);

        TransformerFactory factory = TransformerFactory.newInstance();

 */
public class SystemLogger implements Logger {
    private final PrintWriter out;
    private final Level threshold;

    public SystemLogger(@Nullable OutputStream out) {
        this(out, null);
    }

    public SystemLogger(@Nullable OutputStream out, @Nullable Level threshold) {
        this.out = new PrintWriter(toPsOrDef(out, System.err), true);
        this.threshold = Objects.requireNonNullElse(threshold, Level.INFO);

    FileBackedOutputStream out = new FileBackedOutputStream(50);
    ByteSource source = out.asByteSource();

    out.write(data);
    assertThat(source.read()).isEqualTo(data);

    out.close();
    assertThrows(IOException.class, () -> out.write(42));

    // Verify that write had no effect
    assertThat(source.read()).isEqualTo(data);
    out.reset();
  }