public Map<String, Pair<SelectOperator, Table>> getFinalSelectOps() {
      return finalSelectOps;
    }
Merges the new dependencies in dep to the existing dependencies
of (op, ci).

@param op The operator of the column whose dependency is being modified.
@param ci The column info of the associated column.
@param dep The new dependency.
ql/src/java/org/apache/hadoop/hive/ql/optimizer/lineage/LineageCtx.java