CodeDom generic type constraint

Is there a way to generate a class constraint with CodeDom.

Because when I use something like

var method = new CodeMemberMethod();
var genericParam = new CodeTypeParameter("InterfaceType");
genericParam.Constraints.Add("class");
method.TypeParameters.Add(genericParam);

the generated code is like

private InterfaceType GetImpl<InterfaceType>()
    where InterfaceType : @class
{
}

The best workaround i found is to use a leading whitespace before the class

genericParam.Constraints.Add(" class");

But this seems to be at best a workaround.