Validate that a recursive complex-typed property must be nullable

[mikepizzo]

Marking a recursive complex-typed property as non-nullable would lead to an infinite recursion. For example:

⁠<ComplexType Name="myType>
    <Property Name="nested" Type="self.myType" Nullable="false">
</ComplexType>

or

⁠<ComplexType Name="myType>
    <Property Name="nested" Type="self.derivedType" Nullable="false">
</ComplexType>

⁠<ComplexType Name="derivedType" BaseType="self.myType">
    <Property Name="foo" Type="Edm.String">
</ComplexType>

We should validate against the above definitions (similar to our existing rule "ValidationRules.NavigationPropertyWithRecursiveContainmentTargetMustBeOptional"

Assemblies affected

EdmLib.dll

Reproduce steps

Create and validate the above model.

Expected result

A validation error saying that a recursive complex-typed property must be nullable.

Actual result

No error.

Additional detail