private static string EnsureIsEntityAndCall(this IODataConventionBasedLinkGenerator generator, QueryStructuralValue instance, Func <EntitySet, EntityType, IEnumerable <NamedValue>, string> callback)
{
ExceptionUtilities.CheckArgumentNotNull(generator, "generator");
ExceptionUtilities.CheckArgumentNotNull(instance, "instance");
ExceptionUtilities.CheckArgumentNotNull(callback, "callback");
var queryEntityType = instance.Type as QueryEntityType;
ExceptionUtilities.CheckObjectNotNull(queryEntityType, "Entity's type was not a query entity type. Type was: {0}", instance.Type);
return(callback(queryEntityType.EntitySet, queryEntityType.EntityType, instance.GetKeyPropertyValues()));
}