Query: NullConditional is not added to some complex queries with optional navigation and collection with subquery

[maumar]

query:

l1s => l1s.Where(l1 => l1.OneToOne_Optional_FK.OneToMany_Optional.Distinct().Select(l3 => l3.Id).Contains(1))

query model before nav-rewrite:

from Level1 l1 in DbSet<Level1>
where 
    (from Level3 l3 in 
        (from Level3 <generated>_2 in l1.OneToOne_Optional_FK.OneToMany_Optional
        select <generated>_2)
        .Distinct()
    select l3.Id)
    .Contains(1)
select l1

query model after nav-rewrite:

from Level1 l1 in DbSet<Level1>
join Level2 l1.OneToOne_Optional_FK in DbSet<Level2>
on (Nullable<int>) Property(l1, "Id") equals Property(l1.OneToOne_Optional_FK, "Level1_Optional_Id") into l1.OneToOne_Optional_FK_group
from Level2 l1.OneToOne_Optional_FK in 
    (from Level2 l1.OneToOne_Optional_FK_groupItem in l1.OneToOne_Optional_FK_group
    select l1.OneToOne_Optional_FK_groupItem)
    .DefaultIfEmpty()
where 
    (from Level3 l3 in 
        (from Level3 <generated>_2 in DbSet<Level3>
        where (Nullable<int>) Property(l1.OneToOne_Optional_FK, "Id") == Property(<generated>_2, "OneToMany_Optional_InverseId")
        select <generated>_2)
        .Distinct()
    select l3.Id)
    .Contains(1)
select l1

Problem here is that we don't introduce null check for left key access of

where (Nullable<int>) Property(l1.OneToOne_Optional_FK, "Id") == Property(<generated>_2, "OneToMany_Optional_InverseId")

l1.OneToOne_Optional_FK is optional navigation, so the key access could cause null ref.

This is only problem for InMemory - when we introduce the null check we need to make sure that this null check will be optimized for relational, so that we don't get worse queries.

[maumar]

Fixed in 0bc7be5