After the documentation update on how to utilize the director feature with
commit @17b1c1c the 'callback' and 'extend' examples needed an update as well.
The 'callback' and 'extend' examples were presumed to be obsoleted by the new
'director' example. The examples are helpful though to have similar examples
across target languages and hence the commit @5e88857 which removed these
examples got reverted.
