public void addPredicate(Operator<? extends OperatorDesc> op, Predicate cond) {
      Set<Predicate> conds = condMap.get(op);
      if (conds == null) {
        conds = new LinkedHashSet<Predicate>();
        condMap.put(op, conds);
      }
      for (Predicate p: conds) {
        if (StringUtils.equals(cond.getExpr(), p.getExpr())) {
          p.getBaseCols().addAll(cond.getBaseCols());
          return;
        }
      }
      conds.add(cond);
    }
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