private val data = Buffer()
  private val random = Random(0)

  /**
   * Check all data as verified inside of the test. We do this in an AfterEachCallback so that
   * exceptions thrown from the test do not cause this check to fail.
   */
  @RegisterExtension
  val noDataLeftBehind =
    AfterEachCallback { context: ExtensionContext ->
      if (context.executionException.isPresent) return@AfterEachCallback

        List<String> messages = new ArrayList<>();

        @Override
        public void add(Severity severity, String message, int line, int column, Exception cause) {
            messages.add(message);
        }
    }

          coordinatorWakeUpAt = now + minDelayNanos
          try {
            backend.coordinatorWait(this@TaskRunner, minDelayNanos)
          } catch (_: InterruptedException) {
            // Will cause all tasks to exit unless more are scheduled!
            cancelAll()
          } finally {
            coordinatorWaiting = false
          }
        }
      }
    }
  }

  fun sendFrame(): Http2Writer {
    outFrames.add(OutFrame(frameCount++, bytesOut.size, false))
    return writer
  }

  /**
   * Shortens the last frame from its original length to `length`. This will cause the peer to
   * close the socket as soon as this frame has been written; otherwise the peer stays open until
   * explicitly closed.
   */
  fun truncateLastFrame(length: Int): Http2Writer {

func convPartErrToInt(err error) int {
	err = unwrapAll(err)
	switch err {
	case nil:
		return checkPartSuccess
	case errFileNotFound, errFileVersionNotFound:
		return checkPartFileNotFound
	case errFileCorrupt:
		return checkPartFileCorrupt
	case errVolumeNotFound:
		return checkPartVolumeNotFound
	case errDiskNotFound:
		return checkPartDiskNotFound
	default:
		return checkPartUnknown
	}
}

        SmbSessionImpl session = newSession();

        // Case 1: digest already set -> false
        SMBSigningDigest dg = mock(SMBSigningDigest.class);
        setField(session, "digest", dg);
        assertFalse(session.isSignatureSetupRequired());

        // Case 2: no digest, signing enforced by transport -> true
        setField(session, "digest", null);

      try {
        stimuli[i].executeAndCompare(reference, target);
        verify(reference.getElements());
      } catch (AssertionError cause) {
        throw new AssertionError("failed with stimuli " + subListCopy(stimuli, i + 1), cause);
      }
    }
  }

  private static List<Object> subListCopy(Object[] source, int size) {
    Object[] copy = new Object[size];

#### Internal API changes

The `okhttp3.internal` package is not a published API and we change it frequently without warning.
Depending on code in this package is bad and will cause you problems with any upgrade! But the 4.x
will be particularly painful to naughty developers that import from this package! We changed a lot
to take advantage of sweet Kotlin features.

#### Credentials.basic()

        } catch (Exception // sneaky checked exception
            | Error atomicReferenceFieldUpdaterFailure) {
          // Some Android 5.0.x Samsung devices have bugs in JDK reflection APIs that cause
          // getDeclaredField to throw a NoSuchFieldException when the field is definitely there.
          // For these users fallback to a suboptimal implementation, based on synchronized. This

3. Add tests
4. Handle resources properly (try-with-resources)
5. Consider thread safety
6. Update JavaDoc

### When Fixing Bugs

1. Write failing test first
2. Understand root cause
3. Minimal changes
4. Verify no regressions

### When Refactoring

1. Preserve behavior
2. Keep tests green
3. Small incremental steps
4. Don't mix with new features