public UniqueConstraintConfiguration <TEntity> HasUnique(string propertyName)
    {
        var result = new UniqueConstraintConfiguration <TEntity>();

        result.WithColumn(propertyName);
        return(result);
    }
    public UniqueConstraintConfiguration <TEntity> HasUnique <TProperty>(Expression <Func <TEntity, TProperty> > property)
    {
        var result = new UniqueConstraintConfiguration <TEntity>();

        result.WithColumn(property);
        return(result);
    }