public static RewritablePKFKJoinInfo of(boolean rewritable, List<RexNode> nullableNodes) {
      return new RewritablePKFKJoinInfo(rewritable, nullableNodes);
    }
Returns a triple where first value represents whether we could extract a FK-PK join
or not, the second value is a pair with the column from left and right input that
are used for the FK-PK join, and the third value are the predicates that are not
part of the FK-PK condition. Currently we can only extract one FK-PK join.
ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/HiveRelOptUtil.java