Major Description
After the optimization of RexSimplify,the expression 'x is not null and x <> 5' (x is nullable) is optimized to 'x<> 5' (RexSimplify#unknownAsFalse is true). I think it is not a correct result because when x is null, null<> 5 should return true,while 'x is not null and x <> 5' return false.
I think the optimization for "is not null" in RexSimplify#simplifyAnd2ForUnknownAsFalse should exclude the case of not-equal operator.
I really confused with this optimization, can you give some suggestion,thanks!