Check if HepPlanner should allow to register non-nullable column as an equivalent to nullable

java.lang.AssertionError: Cannot add expression of different type to set:
set type is RecordType(INTEGER NEWCOL) NOT NULL
expression type is RecordType(INTEGER NOT NULL NEWCOL) NOT NULL
set is rel#9105:LogicalProject.(input=HepRelVertex#9104,exprs=[+($0, CASE(=('a', 'a'), 1, null:INTEGER))])
expression is LogicalProject(NEWCOL=[+($0, 1)])
  LogicalTableScan(table=[[CATALOG, SALES, EMP]])

	at org.apache.calcite.plan.RelOptUtil.verifyTypeEquivalence(RelOptUtil.java:380)
	at org.apache.calcite.plan.hep.HepRuleCall.transformTo(HepRuleCall.java:58)
	at org.apache.calcite.plan.RelOptRuleCall.transformTo(RelOptRuleCall.java:268)
	at org.apache.calcite.plan.RelOptRuleCall.transformTo(RelOptRuleCall.java:283)
	at org.apache.calcite.rel.rules.ReduceExpressionsRule$ProjectReduceExpressionsRule.onMatch(ReduceExpressionsRule.java:310)
	at org.apache.calcite.plan.AbstractRelOptPlanner.fireRule(AbstractRelOptPlanner.java:333)
	at org.apache.calcite.plan.hep.HepPlanner.applyRule(HepPlanner.java:542)
	at org.apache.calcite.plan.hep.HepPlanner.applyRules(HepPlanner.java:407)
	at org.apache.calcite.plan.hep.HepPlanner.executeInstruction(HepPlanner.java:243)
	at org.apache.calcite.plan.hep.HepInstruction$RuleInstance.execute(HepInstruction.java:127)
	at org.apache.calcite.plan.hep.HepPlanner.executeProgram(HepPlanner.java:202)
	at org.apache.calcite.plan.hep.HepPlanner.findBestExp(HepPlanner.java:189)
	at org.apache.calcite.test.RelOptTestBase.checkPlanning(RelOptTestBase.java:122)
	at org.apache.calcite.test.RelOptTestBase.access$000(RelOptTestBase.java:64)
	at org.apache.calcite.test.RelOptTestBase$Sql.check(RelOptTestBase.java:303)
	at org.apache.calcite.test.RelOptTestBase$Sql.check(RelOptTestBase.java:282)
	at org.apache.calcite.test.RelOptRulesTest.checkReduceNullableToNotNull(RelOptRulesTest.java:2854)
	at org.apache.calcite.test.RelOptRulesTest.testReduceNullableToNotNull2(RelOptRulesTest.java:2871)