EnumerableHashJoin and EnumerableMergeJoin on composite key return rows matching condition 'null = null'

select 
  emps.empid
from 
  emps a join emps b
on a.deptno = b.deptno
and a.commission = b.commission;

  INSERT INTO "emps" VALUES (100, 10, 'Bill', 10000, 1000);
  INSERT INTO "emps" VALUES (200, 20, 'Eric', 8000, 500);
  INSERT INTO "emps" VALUES (150, 10, 'Sebastian', 7000, null);
  INSERT INTO "emps" VALUES (110, 10, 'Theodore', 11500, 250); 

@Test void testHashJoinWithCompositeKeyAndNullValues() {
  // Both join side 'commission' a limited to null, so a.commission = b.commission should always be false.
  // So all columns in right table b are expected to be null, this sql should result in 0 rows.
  final String sql = "select * from\n"
      + " (select empid, salary, commission from emps where commission is null) as a\n"
      + " left join\n"
      + " (select empid, salary, commission from emps where commission is null) as b\n"
      + " on a.salary = b.salary and a.commission = b.commission\n"
      + " where b.empid is not null";

  CalciteAssert.that()
      .with(CalciteConnectionProperty.LEX, Lex.JAVA)
      .with(CalciteConnectionProperty.FORCE_DECORRELATE, false)
      .withSchema("s", new ReflectiveSchema(new HrSchemaBig()))
      .query(sql)
      .withHook(Hook.PLANNER, (Consumer<RelOptPlanner>) planner -> {
        planner.removeRule(EnumerableRules.ENUMERABLE_JOIN_RULE);
        planner.addRule(EnumerableRules.ENUMERABLE_MERGE_JOIN_RULE);
      })
      .explainContains("EnumerableHashJoin")
      .returnsCount(0)
  ;
}