Nullable attribute missing for collection type reference.

[chrisspre]

In section 7.2.1 Nullable the standard states that

In OData 4.01 responses a collection-valued property MUST specify a value for the Nullable attribute.

If no value is specified for a collection-valued property, the client cannot assume any default value. Clients SHOULD be prepared for this situation even in OData 4.01 responses.

but the EDM library leaves out the Nullable attribute, in all cases.

Assemblies affected

Microsoft.OData.Edm -Version 7.8.3

Reproduce steps

The C# code

      @type.AddProperty(new EdmStructuralProperty(@type, "f",
          new EdmCollectionTypeReference(new EdmCollectionType(
             new EdmDecimalTypeReference(@decimal, true)))));

produces CSDL of the form

<Property Name="f" Type="Collection(Edm.Decimal)" />

that is missing the explicit Nullable attribute as stated in the standard

Expected result

<Property Name="f" Type="Collection(Edm.Decimal)" Nullable="true"/>

Actual result

<Property Name="f" Type="Collection(Edm.Decimal)" />

[habbes]

@chrisspre I think you mixed up the "expected" and "actual" results in the issue description?

[chrisspre]

@chrisspre I think you mixed up the "expected" and "actual" results in the issue description?

Yes, sorry. fixed it.

[xuzhg]

If the type is collection and nullable of element is true, we should write the nullable="true".

See the code at: https://github.com/OData/odata.net/blob/master/src/Microsoft.OData.Edm/Csdl/Serialization/EdmModelCsdlSchemaWriter.cs#L108

[chrisspre]

will be addressed in #2034