private JobConf initializeVertexConf(JobConf conf, Context context, MergeJoinWork work) {
    if (work.getMainWork() instanceof MapWork) {
      return initializeVertexConf(conf, context, (MapWork) (work.getMainWork()));
    } else {
      return initializeVertexConf(conf, context, (ReduceWork) (work.getMainWork()));
    }
  }
Creates and initializes the JobConf object for a given BaseWork object.

@param conf Any configurations in conf will be copied to the resulting new JobConf object.
@param work BaseWork will be used to populate the configuration object.
@return JobConf new configuration object
ql/src/java/org/apache/hadoop/hive/ql/exec/tez/DagUtils.java