This implementation of Close calls the TextWriter.Dispose(bool) method and passes it a true value.
Flushing the stream will not flush its underlying encoder unless you explicitly call TextWriter.Flush or Close. Setting the StreamWriter.AutoFlush property to true means that data will be flushed from the buffer to the stream, but the encoder state will not be flushed. This allows the encoder to keep its state (partial characters) so that it can encode the next block of characters correctly. This scenario affects UTF8 and UTF7 where certain characters can be encoded only after the encoder receives the adjacent character or characters.
In derived classes, do not override the TextWriter.Close method. Instead, override the TextWriter.Dispose(bool) method to add code for releasing resources.