@Override
  public void onMatch(RelOptRuleCall call) {
    Filter filter = call.rel(0);
    Join join = call.rel(1);
    super.perform(call, filter, join);
  }
Rule that tries to push filter expressions into a join condition and into
the inputs of the join.
ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/rules/jdbc/JDBCFilterJoinRule.java