InputStreamDataSource is an implementation of the javax.activation.DataSource It is designed to be used by SOAPMailSender as a bridge of InputStream and OutputStream for base64 encoding transformation.
Author: Philip Wong
Returns new byte array from a new BytesArrayOutStream always. Logically, it is required to copy binary content from the input stream to output stream. But it is found the same result without touching binary content.
Returns: the content type when this data source created.