code: public CallOptions withDeadline(@Nullable Deadline deadline) {
      CallOptions newOptions = new CallOptions(this);
      newOptions.deadline = deadline;
      return newOptions;
    }
docs: Returns a new {@code CallOptions} with the given absolute deadline.
  
  <p>This is mostly used for propagating an existing deadline. {@link #withDeadlineAfter} is the
  recommended way of setting a new deadline,
  
  @param deadline the deadline or {@code null} for unsetting the deadline.