The "old" MapReduce API in org.apache.hadoop.mapred was deprecated in
the 0.20 release series when the "new" (Context Objects) MapReduce API
was added in org.apache.hadoop.mapreduce. Unfortunately, the new API
was not complete in 0.20 and most users stayed with the old API. This
has led to the confusing situation where the old API is generally
recommended, even though it is deprecated.
To remedy this situation I suggest that we remove deprecations from
the old API in 0.20 and trunk, and mark the new API as "Evolving" (see
MAPREDUCE-1623 for the latter). This would mean a few things:
* The next 0.20 release would have a non-deprecated old API.
* The forthcoming 0.21 release would have a "Stable" (non-deprecated)
old API, and a "Evolving" new API.
* For some pre-1.0 release (perhaps 0.22), the old API could be
deprecated again, and the new API marked as "Stable".
* In the 1.0 release it would be possible to remove the old API.