public Task WriteToAsync( FormatOptions options, Stream stream, CancellationToken cancellationToken = default )
options is null.
stream is null.
|ObjectDisposedException||The MimeEntity has been disposed.|
|OperationCanceledException||The operation was canceled via the cancellation token.|
|IOException||An I/O error occurred.|
Asynchronously writes the headers to the output stream, followed by a blank line.
Subclasses should override this method to write the content of the entity.