@Override
    public boolean isLoaded(I id) {
        return this.objects.containsKey(sanitizeIdentifier(id));
    }
An abstract manager class

@param <I> the class used to identify each object held in this manager
@param <C> the super class being managed
@param <T> the implementation class this manager is "managing"
common/src/main/java/me/lucko/luckperms/common/model/manager/AbstractManager.java