Currently, default values for properties and (now, as of
ODATA-1066) parameters are static values.
There are some cases where the default value may be the result of a calculation. Examples:
1) The value of a related property/parameter
2) An expression based on the value of one (or more) related properties/parameters
3) The result of invoking a function(import) on the service (with params?)
-how to express the value of the defaultvalue (use Edm.Untyped? – this could only be supported in 4.01)
-what is the syntax of the expression?
-can it invoke a funciton(import) and, if so, how are parameters passed?
For parameters, could define a derived OptionalParameterType that has a DefaultValueExpression that is Edm.Untyped and only returned as that derived type in a 4.01 payload.