add the build-in abstract types for the core model

[xuzhg]

Issues

*See Issue: #1027

Description

OData spec says at: http://docs.oasis-open.org/odata/odata/v4.0/errata03/os/complete/part3-csdl/odata-v4.0-errata03-os-part3-csdl-complete.html#_Built-In_Abstract_Types

The following built-in abstract types can be used within a model:
· Edm.PrimitiveType
· Edm.ComplexType
· Edm.EntityType

Vocabulary terms can, in addition, use
· Edm.AnnotationPath
· Edm.PropertyPath
· Edm.NavigationPropertyPath

However, the current implementation doesn't include this part. It will make the model validation failed. Show as #1027

Note:

It's not a checkin-able PR. it's just for discuss about the design and implementation about the abstract type. So, don't care about the wrong comments and not correct test cases.

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Checklist (Uncheck if it is not completed)

• Test cases added
• Build and test with one-click build and test script passed

Additional work necessary

[xuzhg]

@mikepizzo Can we discuss it in next Monday's meeting?

[xuzhg]

More context:

We can't define the Edm Term with the correct type if we don't define the above abstract type.

For example:

I want to call:

EdmModel model = new EdmModel();
EdmComplexType complexType = new EdmComplexType("NS", "SelectType");
complexType.AddStructuralProperty("DefaultSelect", new EdmCollectionTypeReference(new EdmCollectionType(EdmCoreModel.Instance.GetString(true))));
complexType.AddStructuralProperty("DefaultHidden", new EdmCollectionTypeReference(new EdmCollectionType(EdmCoreModel.Instance.GetString(true))));
model.AddElement(complexType);
EdmTerm term = new EdmTerm("NS", "MyTerm", new EdmComplexTypeReference(complexType, true));
model.AddElement(term);

We can get:

<Schema Namespace="NS" xmlns="http://docs.oasis-open.org/odata/ns/edm">
      <ComplexType Name="SelectType">
             <Property Name="DefaultSelect" Type="Collection(Edm.String)" />
             <Property Name="DefaultHidden" Type="Collection(Edm.String)" />
      </ComplexType>
     <Term Name="MyTerm" Type="NS.SelectType" />
</Schema>

We can't define the Type as "Collection(Edm.NavigationPropertyPath)"

[xuzhg]

Discussion done. Close it. Will file a new PR.