List enterprises within groups on DFC API

engines/dfc_provider/app/services/enterprise_builder.rb

@@ -20,10 +20,20 @@ class EnterpriseBuilder < DfcBuilder
   end
 
   def self.enterprise_group(group)
+    members = group.enterprises.map do |member|
+      urls.enterprise_url(member.id)
+    end
+
     DataFoodConsortium::Connector::Enterprise.new(
       urls.enterprise_group_url(group.id),
       name: group.name,
       description: group.description,
-    )
+    ).tap do |enterprise|
+      # This property has been agreed by the DFC but hasn't made it's way into
+      # the Connector yet.
+      enterprise.registerSemanticProperty("dfc-b:affiliatedBy") do
+        members
+      end
+    end
   end
 end

engines/dfc_provider/spec/requests/enterprise_groups_spec.rb

@@ -4,7 +4,13 @@ require_relative "../swagger_helper"
 
 describe "EnterpriseGroups", type: :request, swagger_doc: "dfc.yaml", rswag_autodoc: true do
   let(:user) { create(:oidc_user) }
-  let(:group) { create(:enterprise_group, id: 60_000) }
+  let(:group) {
+    create(
+      :enterprise_group,
+      id: 60_000, name: "Sustainable Farmers", enterprises: [enterprise],
+    )
+  }
+  let(:enterprise) { create(:enterprise, id: 10_000) }
 
   before { login_as user }
 
@@ -16,7 +22,12 @@ describe "EnterpriseGroups", type: :request, swagger_doc: "dfc.yaml", rswag_auto
       response "200", "successful" do
         let(:id) { group.id }
 
-        run_test!
+        run_test! do
+          expect(json_response).to include(
+            "dfc-b:hasName" => "Sustainable Farmers",
+            "dfc-b:affiliatedBy" => "http://test.host/api/dfc/enterprises/10000",
+          )
+        end
       end
     end
   end

swagger/dfc.yaml

@@ -256,9 +256,10 @@ paths:
                     "@context": https://www.datafoodconsortium.org
                     "@id": http://test.host/api/dfc/enterprise_groups/60000
                     "@type": dfc-b:Enterprise
-                    dfc-b:hasName: Enterprise group
+                    dfc-b:hasName: Sustainable Farmers
                     dfc-b:hasDescription: this is a group
                     dfc-b:VATnumber: ''
+                    dfc-b:affiliatedBy: http://test.host/api/dfc/enterprises/10000
   "/api/dfc/enterprises/{id}":
     get:
       summary: Show enterprise