Support for nested columns

I would like to be able to use nested fields in table definitions, like BigQuery structs and arrays, which is not possible now as far as I understand.The idea is to be able to list and document nested columns as well as named columns inside the nested column. Something like:

Table products {
  product_id int
  title string
  nested_field1 struct {
    field_inside1 date
    field_inside2 int
    field_inside3 string
    ...
  }
  ...
}