Javadoc
Wrapper arround an OutputStream to allow the output to be generated.
Generated output really just means that the loop that writes content to
the OutputStream is in the custom code rather than the HttpTransfer
implementation. This could be code that reads from some other source,
such as read a ResultSet from a query and write to a servlet output
(streaming output) or read from a servlet InputStream and write to an HttpUpload
(proxying an upload).