@Override
  public <A> void read(
      ByteBuffer dst,
      long position,
      @Nullable A attachment,
      CompletionHandler<Integer, ? super A> handler) {
    addCallback(read(dst, position), handler, attachment);
  }
{@link AsynchronousFileChannel} implementation that delegates to a {@link JimfsFileChannel}.

@author Colin Decker
jimfs/src/main/java/com/google/common/jimfs/JimfsAsynchronousFileChannel.java