private Object getObject(EntityUniqueIdentifier belongsTo) {
        //System.out.println("BelongsTo: " + belongsTo);
        if (this.maintypes.containsKey(belongsTo)) {
            return this.maintypes.get(belongsTo);
        } else {

            for (Relation key : this.referenceTypes.keySet()) {
                //System.out.println(" -> " + key.getUuidOfObject());
                if (key.getUuidOfObject().equals(belongsTo)) {
                    return this.referenceTypes.get(key);
                }
            }
        }
        System.out.println("belongs to: " + belongsTo);
        throw new IllegalArgumentException(
            "cause of only grabbing existing references, it should never happen to get here");
    }