Trying to layout a request definition in swagger-blocks

[bopritchard]

what would be the equivalent in swagger-blocks

extension:
  type: array
  items:
    oneOf:
      - $ref: '#/definitions/Race'
      - $ref: '#/definitions/Ethnicity'

I've tried

    property :extension do
      key :type, :array
      items do
        key :type, :object
        oneOf do
          key :'$ref', :Race
          key :'$ref', :Ethnicity
          key :'$ref', :Ethnicity
        end
      end
    end

but get the following exception

undefined method `oneOf' for #<Swagger::Blocks::Nodes::ItemsNode

[tanekz1]

![build_a_mod_3](https://user-images.githubuse

rcontent.com/59726904/72142974-20929180-3353-11ea-9263-549d94645f1b.png)