Cannot Attach Entity to DataServiceContext if Entity Key is an Enum

[noahsrc]

I am hitting an error when detaching a tracked entity from a DataServiceContext, then attaching it to the same context at a later time. This is occurring with entities that contain an enumeration type as a key. It seems enum keys are not supported for the DataServiceContext.AttachTo method.

Assemblies affected

OData.Core (.NET Framework) v7.21.4

Reproduce steps

var context = *set up context*

// Retrieve entity that contains an enumeration key. In this case, the keys are orderNo (string) and documentType (enum)
DataServiceCollection<SalesOrder> orderCollection = new DataServiceCollection<SalesOrder>(context.SalesOrders.Where(so => so.OrderNo == "S-ORD101010" && so.DocumentType == SalesDocumentType.Order));

object entity = context.Entities.First().Entity;

context.Detach(entity);

// Attaching throws exception
context.AttachTo("SalesOrders", entity);

Expected result

The entity is attached to the DataServiceContext.

Actual result

The entity is not attached to the DataServiceContext and an error is thrown:

A value with primitive kind 'Enum' cannot be converted into a primitive object value.

Additional detail

The full exception reads:

Microsoft.OData.ODataException: A value with primitive kind 'Enum' cannot be converted into a primitive object value.
   at Microsoft.OData.Client.EdmValueUtils.ToClrValue(IEdmPrimitiveValue edmValue)
   at Microsoft.OData.Client.DataServiceUrlKeyDelimiter.<>c__DisplayClass9_0`1.<AppendKeyExpression>b__0(T p)
   at Microsoft.OData.Client.KeySerializer.GetKeyValueAsString[TProperty](Func`2 getPropertyValue, TProperty property, LiteralFormatter literalFormatter)
   at Microsoft.OData.Client.KeySerializer.AppendKeyWithParentheses[TProperty](StringBuilder builder, ICollection`1 keyProperties, Func`2 getPropertyName, Func`2 getPropertyValue)
   at Microsoft.OData.Client.DataServiceUrlKeyDelimiter.AppendKeyExpression(IEdmStructuredValue entity, StringBuilder builder)
   at Microsoft.OData.Client.ConventionalODataEntityMetadataBuilder.ConventionalODataUriBuilder.BuildEntityInstanceUri(Uri baseUri, IEdmStructuredValue entityInstance)
   at Microsoft.OData.Client.DataServiceContext.AttachTo(String entitySetName, Object entity, String etag)

An additional switch case for Enums may need to be added in the ToClrValue method in Microsoft.OData.Core/Evaluation/EdmValueUtils.cs.

On initial inspection, adding this case solves the issue:

case EdmValueKind.Enum:
    return ((IEdmEnumValue)edmValue).Value.Value;