private Guid MapAndCheckUid(Guid libraryUid)
{
if (libraryUid == Guid.Empty)
libraryUid = _default;
if (libraryUid == Guid.Empty)
throw new InvalidOperationException("No default library has been set for this manager.");
if (!_pools.ContainsKey(libraryUid))
throw new ArgumentException("The specified library has not been registered with this manager.");
return libraryUid;
}