THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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a. there is a join (let's call it J1.) in the nested plan,
b. if J1 is an inner join, one input pipeline of J1 has a NestedTupleSource descendant (let's call it N1),
c. if J1 is a left outer join, the left branch of J1 has a NestedTupleSource descendant (let's call it N1),
d. there is no tuple dropping from N1 to J1
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