In order to add this '[Serf]' to the Option Set, you must also add its '[King]'--if you continue it will not be added to the Option Set

public static FailureDefinitionId MustAddKing { get; }

Public Shared ReadOnly Property MustAddKing As FailureDefinitionId
	Get

public:
static property FailureDefinitionId^ MustAddKing {
	FailureDefinitionId^ get ();
}