code: public final S withDeadline(@Nullable Deadline deadline) {
      return build(channel, callOptions.withDeadline(deadline));
    }
docs: Returns a new stub with an absolute deadline.
  
  <p>This is mostly used for propagating an existing deadline. {@link #withDeadlineAfter} is the
  recommended way of setting a new deadline,
  
  @since 1.0.0
  @param deadline the deadline or {@code null} for unsetting the deadline.