return b == null ? null : checkNotNull(doBackward(b));
    } else {
      return unsafeDoBackward(b);
    }
  }

  /*
   * LegacyConverter violates the contract of Converter by allowing its doForward and doBackward
   * methods to accept null. We could avoid having unchecked casts in Converter.java itself if we

    checkNotNull(listener, "Runnable was null.");
    checkNotNull(executor, "Executor was null.");
    // Checking isDone and listeners != TOMBSTONE may seem redundant, but our contract for
    // addListener says that listeners execute 'immediate' if the future isDone(). However, our
    // protocol for completing a future is to assign the value field (which sets isDone to true) and

    // They aren't equal...
    assertFalse(hashCodeA.equals(hashCodeB));

    // But they still have the same Object#hashCode() value.
    // Technically not a violation of the equals/hashCode contract, but...?
    assertEquals(hashCodeA.hashCode(), hashCodeB.hashCode());
  }

  public void testRoundTripHashCodeUsingFromString() {
    HashCode hash1 = sha1().hashString("foo", US_ASCII);

    // They aren't equal...
    assertFalse(hashCodeA.equals(hashCodeB));

    // But they still have the same Object#hashCode() value.
    // Technically not a violation of the equals/hashCode contract, but...?
    assertEquals(hashCodeA.hashCode(), hashCodeB.hashCode());
  }

  public void testRoundTripHashCodeUsingFromString() {
    HashCode hash1 = sha1().hashString("foo", US_ASCII);

 * elements, if there is no comparator) to test element equality. As a result, if the comparator is
 * not consistent with equals, some of the standard implementations may violate the {@code Set}
 * contract.
 *
 * <p>The {@code standard} methods and the collection views they return are not guaranteed to be
 * thread-safe, even when all of the methods that they depend on are thread-safe.
 *
 * @author Louis Wasserman

  }

  // TODO(chrisn): Consider trying to encode/flush directly to the argument byte
  // buffer when possible.
  @Override
  public int read(byte[] b, int off, int len) throws IOException {
    // Obey InputStream contract.
    checkPositionIndexes(off, off + len, b.length);
    if (len == 0) {
      return 0;
    }

    // The rest of this method implements the process described by the CharsetEncoder javadoc.

        }, "EmptyIterator should work correctly in nested iteration");
    }

    @Test
    @DisplayName("EmptyIterator should follow Iterator contract for empty collections")
    void testIteratorContract() {
        // Given - typical Iterator usage pattern

        // When & Then - verify empty collection behavior

/**
 * Unit tests for {@link SmbComTransactionResponse}.
 *
 * <p>The class is abstract, so a concrete stub implementation is
 * provided purely to expose protected state and to satisfy the abstract
 * method contract.  The tests focus on public API behaviour and the
 * parsing logic in {@code readParameterWordsWireFormat} and
 * {@code readBytesWireFormat}.
 */
public class SmbComTransactionResponseTest {

      boolean result = sync.setException(checkNotNull(throwable));
      if (result) {
        executionList.execute();
      }
      return result;
    }

    /**
     * Following the contract of {@link AbstractQueuedSynchronizer} we create a private subclass to
     * hold the synchronizer. This synchronizer is used to implement the blocking and waiting calls

            // Simple test implementation - not used in these tests
            return 0;
        }
    }

    @Nested
    @DisplayName("Interface Contract Tests")
    class InterfaceContractTests {

        @Test
        @DisplayName("Should implement FileSystemInformation interface")
        void shouldImplementFileSystemInformation() {