List all newsgroups served by the NNTP server. If no newsgroups are served, no entries will be returned. The method uses the "LIST" command.
@return An iterable of NewsgroupInfo instances containing the informationfor each newsgroup served by the NNTP server. If no newsgroups are served, no entries will be returned.
@exception NNTPConnectionClosedException If the NNTP server prematurely closes the connection as a result of the client being idle or some other reason causing the server to send NNTP reply code 400. This exception may be caught either as an IOException or independently as itself.
@exception IOException If an I/O error occurs while either sending acommand to the server or receiving a reply from the server.
@since 3.0