public Map<String, List<ExprNodeDesc>> getFinalCandidates() {
    return pushdownPreds;
  }
Returns the list of pushdown expressions for each alias that appear in the
current operator's RowResolver. The exprs in each list can be combined
using conjunction (AND).

@return the map of alias to a list of pushdown predicates
ql/src/java/org/apache/hadoop/hive/ql/ppd/ExprWalkerInfo.java