LINQ translation for Nullable<T>.HasValue incorrectly translates to IS_DEFINED() - should be (NOT IS_NULL()) OR IS_DEFINED()

[DaRosenberg]

Describe the bug

There is LINQ translation support for Nullable<T>.HasValue in the v3 SDK. However, the translation assumes the property must be missing or undefined in the underlying document. It ignores the fact that it might also be null and that the .HasValue property in .NET is the idiomatic (and only) way to query for that, given that .NET lacks any distinction between null and undefined.

To Reproduce

void Main()
{
    var client = new CosmosClient("connectionString", new CosmosClientOptions());
    var container = client.GetContainer("x", "y");
    var query =
        container.GetItemLinqQueryable<C>()
    	    .Where(x => !x.NullableValue.HasValue);
    Console.WriteLine(query.ToQueryDefinition());	
}

public class C
{
    public DateTime? NullableValue { get; set; }
}

Expected behavior

SELECT VALUE root FROM root WHERE ((NOT IS_DEFINED(root["nullableValue"])) OR IS_NULL(root["nullableValue"]))

Actual behavior

SELECT VALUE root FROM root WHERE (NOT IS_DEFINED(root["nullableValue"]))

(This misses documents where nullableValue == null in the database.)

Environment summary

SDK Version: 3.41.0

[HEBOS]

I'd say that using HasValue should be redundant.
I'd expect this:

var query = container.GetItemLinqQueryable<C>() .Where(x => !x.NullableValue);
to be translated to the same SQL code:

SELECT VALUE root FROM root WHERE ((NOT IS_DEFINED(root["nullableValue"])) OR IS_NULL(root["nullableValue"]))

In other words, why would we need to pass "!nullableValue.HasValue" at all?
It makes code very hard to maintain.

[DaRosenberg]

@HEBOS That will not even compile I think - you can't use a Nullable<T> as a boolean expression C# (like you can in JavaScript). You can only do compare it to null or use the HasValue property.