Conversion from Nullable Enum to Enum fails with exception for LINQ3 Provider

Working with Data Drivers
,
1

Hi guys, after upgrading MongoDB.Driver.GridFS from 2.9.2 to 2.22. I started seeing an exception:

MongoDB.Driver.Linq.ExpressionNotSupportedException : Expression not supported: Convert(x.SomeType).
....
--ExpressionNotSupportedException
   at MongoDB.Driver.Linq.Linq3Implementation.Translators.ExpressionToFilterTranslators.ToFilterFieldTranslators.ConvertExpressionToFilterFieldTranslator.Translate(TranslationContext context, UnaryExpression expression)
   at MongoDB.Driver.Linq.Linq3Implementation.Translators.ExpressionToFilterTranslators.ToFilterFieldTranslators.ConvertExpressionToFilterFieldTranslator.Translate(TranslationContext context, UnaryExpression expression)
   at MongoDB.Driver.Linq.Linq3Implementation.LinqProviderAdapterV3.TranslateExpressionToField[TDocument,TField](Expression`1 expression, IBsonSerializer`1 documentSerializer, IBsonSerializerRegistry serializerRegistry, Boolean allowScalarValueForArrayField)
   at MongoDB.Driver.SingleItemAsArrayOperatorFilterDefinition`2.Render(IBsonSerializer`1 documentSerializer, IBsonSerializerRegistry serializerRegistry, LinqProvider linqProvider)
   at MongoDB.Driver.AndFilterDefinition`1.Render(IBsonSerializer`1 documentSerializer, IBsonSerializerRegistry serializerRegistry, LinqProvider linqProvider)
   at MongoDB.Driver.AndFilterDefinition`1.Render(IBsonSerializer`1 documentSerializer, IBsonSerializerRegistry serializerRegistry, LinqProvider linqProvider)
   at MongoDB.Driver.MongoCollectionImpl`1.CreateCountDocumentsOperation(FilterDefinition`1 filter, CountOptions options)
   at MongoDB.Driver.MongoCollectionImpl`1.CountDocumentsAsync(IClientSessionHandle session, FilterDefinition`1 filter, CountOptions options, CancellationToken cancellationToken)
   at MongoDB.Driver.MongoCollectionImpl`1.<>c__DisplayClass40_0.<CountDocumentsAsync>b__0(IClientSessionHandle session)
   at MongoDB.Driver.MongoCollectionImpl`1.<UsingImplicitSessionAsync>d__109`1.MoveNext()

The reason is a conversion from a Nullable to Enum.

Example of Data:

public class TestDocument
{
  [BsonId]
  public Guid Id {get;set;}
  [JsonProperty(Required = Required.AllowNull)]
  public MyEnum? SomeType{ get;set; }
}

public class SomeFilter
{
 public MyEnum SomeType{ get;set; }
}

public DAL
{
public Get(Filter options) 
{
FilterDefinitionBuilder<TestDocument> filterBuilder = Builders<TestDocument>.Filter;
FilterDefinition<TestDocument> filter = filterBuilder.And(filter, filterBuilder.In(x => (MyEnum)x.SomeType, options.SomeType));

IMongoCollection<TestDocument> collection = _databaseR.GetCollection<TestDocument>(CollectionName);

                IFindFluent<TestDocument, TestDocument> resultFind = collection.Find(filter ?? Builders<TestDocument>.Filter.Empty,
                        new FindOptions
                        {
                            Collation = new Collation("en_US", caseLevel: false, strength: CollationStrength.Secondary),
                        });

                var result = new RecordsStorage<BusinessEntity>
                {
                    TotalRecords = await resultFind.CountDocumentsAsync(cancellationToken),
                    Records = (await resultFind.ToListAsync(cancellationToken))
                               .Cast<BusinessEntity>()
                              .ToList(),
                };
}

If I change LinqProvider = MongoDB.Driver.Linq.LinqProvider.V2 - it works as a charm.