public override List<TypeSpec> ResolveMissingDependencies()
{
var missing = returnType.ResolveMissingDependencies ();
foreach (var pt in parameters.Types) {
var m = pt.GetMissingDependencies ();
if (m == null)
continue;
if (missing == null)
missing = new List<TypeSpec> ();
missing.AddRange (m);
}
return missing;
}