Return missing created_at field on reshares endpoint

app/controllers/api/v1/reshares_controller.rb

@@ -25,6 +25,7 @@ module Api
         reshares_page[:data] = reshares_page[:data].map do |r|
           {
             guid:   r.guid,
+            created_at: r.created_at,
             author: PersonPresenter.new(r.author).as_api_json
           }
         end

lib/schemas/api_v1.json

@@ -337,6 +337,20 @@
       ]
     },
 
+    "reshares": {
+      "type": "array",
+      "items": {
+        "type": "object",
+        "properties": {
+          "guid":  { "$ref": "#/definitions/guid" },
+          "created_at": { "$ref": "#/definitions/timestamp" },
+          "author": { "$ref": "#/definitions/short_profile" }
+        },
+        "required": ["guid", "created_at", "author"],
+        "additionalProperties": false
+      }
+    },
+
     "posts": {
       "type": "array",
       "items": { "$ref": "#/definitions/post" }

spec/integration/api/reshares_controller_spec.rb

@@ -55,7 +55,7 @@ describe Api::V1::ResharesController do
         expect(reshare["guid"]).not_to be_nil
         confirm_person_format(reshare["author"], alice)
 
-        expect(reshares.to_json).to match_json_schema(:api_v1_schema)
+        expect(reshares.to_json).to match_json_schema(:api_v1_schema, fragment: "#/definitions/reshares")
       end
 
       it "succeeds but empty with private post it can see" do