diff --git a/spec/requests/api/groups_spec.rb b/spec/requests/api/groups_spec.rb
index e959eae88a0..378ddc40fb2 100644
--- a/spec/requests/api/groups_spec.rb
+++ b/spec/requests/api/groups_spec.rb
@@ -39,25 +39,25 @@ describe 'groups' do
                 mentionable_level: { type: :integer },
                 messageable_level: { type: :integer },
                 visibility_level: { type: :integer },
-                automatic_membership_email_domains: { type: :string, nullable: true },
+                automatic_membership_email_domains: { type: [:string, :null] },
                 automatic_membership_retroactive: { type: :boolean },
                 primary_group: { type: :boolean },
-                title: { type: :string, nullable: true },
-                grant_trust_level: { type: :string, nullable: true },
-                incoming_email: { type: :string, nullable: true },
+                title: { type: [:string, :null] },
+                grant_trust_level: { type: [:string, :null] },
+                incoming_email: { type: [:string, :null] },
                 has_messages: { type: :boolean },
-                flair_url: { type: :string, nullable: true },
-                flair_bg_color: { type: :string, nullable: true },
-                flair_color: { type: :string, nullable: true },
-                bio_raw: { type: :string, nullable: true },
-                bio_cooked: { type: :string, nullable: true },
-                bio_excerpt: { type: :string, nullable: true },
+                flair_url: { type: [:string, :null] },
+                flair_bg_color: { type: [:string, :null] },
+                flair_color: { type: [:string, :null] },
+                bio_raw: { type: [:string, :null] },
+                bio_cooked: { type: [:string, :null] },
+                bio_excerpt: { type: [:string, :null] },
                 public_admission: { type: :boolean },
                 public_exit: { type: :boolean },
                 allow_membership_requests: { type: :boolean },
-                full_name: { type: :string, nullable: true },
+                full_name: { type: [:string, :null] },
                 default_notification_level: { type: :integer },
-                membership_request_template: { type: :string, nullable: true },
+                membership_request_template: { type: [:string, :null] },
                 membership_visibility_level: { type: :integer },
                 can_see_members: { type: :boolean },
                 publish_read_state: { type: :boolean },
diff --git a/spec/requests/api/invites_spec.rb b/spec/requests/api/invites_spec.rb
index cace13aa162..1ed7d22470e 100644
--- a/spec/requests/api/invites_spec.rb
+++ b/spec/requests/api/invites_spec.rb
@@ -20,8 +20,8 @@ describe 'invites' do
           skip_email: { type: :boolean, default: false },
           custom_message: { type: :string, description: "optional, for email invites" },
           max_redemptions_allowed: { type: :integer, example: 5, default: 1, description: "optional, for link invites" },
-          topic_id: { type: :int },
-          group_id: { type: [:int], description: "optional, either this or `group_names`" },
+          topic_id: { type: :integer },
+          group_id: { type: :integer, description: "optional, either this or `group_names`" },
           group_names: { type: :string, description: "optional, either this or `group_id`" },
           expires_at: { type: :string, default: "controlled by invite_expiry_days site setting" },
         }
@@ -34,7 +34,7 @@ describe 'invites' do
           link: { type: :string, example: "http://example.com/invites/9045fd767efe201ca60c6658bcf14158" },
           email: { type: :string, example: "not-a-user-yet@example.com" },
           emailed: { type: :boolean, example: false },
-          custom_message: { type: :string, example: "Hello world!", nullable: true },
+          custom_message: { type: [:string, :null], example: "Hello world!" },
           topics: { type: :array, example: [] },
           groups: { type: :array, example: [] },
           created_at: { type: :string, example: "2021-01-01T12:00:00.000Z" },
diff --git a/spec/requests/api/notifications_spec.rb b/spec/requests/api/notifications_spec.rb
index ae1fa8fcfb2..4100b49954f 100644
--- a/spec/requests/api/notifications_spec.rb
+++ b/spec/requests/api/notifications_spec.rb
@@ -29,9 +29,9 @@ describe 'notifications' do
                 notification_type: { type: :integer },
                 read: { type: :boolean },
                 created_at: { type: :string },
-                post_number: { type: :string, nullable: true },
-                topic_id: { type: :integer, nullable: true },
-                slug: { type: :string, nullable: true },
+                post_number: { type: [:string, :null] },
+                topic_id: { type: [:integer, :null] },
+                slug: { type: [:string, :null] },
                 data: {
                   type: :object,
                   properties: {
diff --git a/spec/requests/api/posts_spec.rb b/spec/requests/api/posts_spec.rb
index 3aab1460201..2b14260dade 100644
--- a/spec/requests/api/posts_spec.rb
+++ b/spec/requests/api/posts_spec.rb
@@ -37,7 +37,7 @@ describe 'posts' do
                 post_type: { type: :integer },
                 updated_at: { type: :string },
                 reply_count: { type: :integer },
-                reply_to_post_number: { type: :string, nullable: true },
+                reply_to_post_number: { type: [:string, :null] },
                 quote_count: { type: :integer },
                 incoming_link_count: { type: :integer },
                 reads: { type: :integer },
@@ -50,17 +50,17 @@ describe 'posts' do
                 topic_html_title: { type: :string },
                 category_id: { type: :integer },
                 display_username: { type: :string },
-                primary_group_name: { type: :string, nullable: true },
-                flair_name: { type: :string, nullable: true },
-                flair_url: { type: :string, nullable: true },
-                flair_bg_color: { type: :string, nullable: true },
-                flair_color: { type: :string, nullable: true },
+                primary_group_name: { type: [:string, :null] },
+                flair_name: { type: [:string, :null] },
+                flair_url: { type: [:string, :null] },
+                flair_bg_color: { type: [:string, :null] },
+                flair_color: { type: [:string, :null] },
                 version: { type: :integer },
                 can_edit: { type: :boolean },
                 can_delete: { type: :boolean },
                 can_recover: { type: :boolean },
                 can_wiki: { type: :boolean },
-                user_title: { type: :string, nullable: true },
+                user_title: { type: [:string, :null] },
                 raw: { type: :string },
                 actions_summary: {
                   type: :array,
@@ -78,12 +78,12 @@ describe 'posts' do
                 user_id: { type: :integer },
                 hidden: { type: :boolean },
                 trust_level: { type: :integer },
-                deleted_at: { type: :string, nullable: true },
+                deleted_at: { type: [:string, :null] },
                 user_deleted: { type: :boolean },
-                edit_reason: { type: :string, nullable: true },
+                edit_reason: { type: [:string, :null] },
                 can_view_edit_history: { type: :boolean },
                 wiki: { type: :boolean },
-                reviewable_id: { type: :string, nullable: true },
+                reviewable_id: { type: [:string, :null] },
                 reviewable_score_count: { type: :integer },
                 reviewable_score_pending_count: { type: :integer },
               }
@@ -130,7 +130,7 @@ describe 'posts' do
       response '200', 'latest posts' do
         schema type: :object, properties: {
           id: { type: :integer },
-          name: { type: :string, nullable: true },
+          name: { type: [:string, :null] },
           username: { type: :string },
           avatar_template: { type: :string },
           created_at: { type: :string },
@@ -139,7 +139,7 @@ describe 'posts' do
           post_type: { type: :integer },
           updated_at: { type: :string },
           reply_count: { type: :integer },
-          reply_to_post_number: { type: :string, nullable: true },
+          reply_to_post_number: { type: [:string, :null] },
           quote_count: { type: :integer },
           incoming_link_count: { type: :integer },
           reads: { type: :integer },
@@ -148,18 +148,18 @@ describe 'posts' do
           yours: { type: :boolean },
           topic_id: { type: :integer },
           topic_slug: { type: :string },
-          display_username: { type: :string, nullable: true },
-          primary_group_name: { type: :string, nullable: true },
-          flair_name: { type: :string, nullable: true },
-          flair_url: { type: :string, nullable: true },
-          flair_bg_color: { type: :string, nullable: true },
-          flair_color: { type: :string, nullable: true },
+          display_username: { type: [:string, :null] },
+          primary_group_name: { type: [:string, :null] },
+          flair_name: { type: [:string, :null] },
+          flair_url: { type: [:string, :null] },
+          flair_bg_color: { type: [:string, :null] },
+          flair_color: { type: [:string, :null] },
           version: { type: :integer },
           can_edit: { type: :boolean },
           can_delete: { type: :boolean },
           can_recover: { type: :boolean },
           can_wiki: { type: :boolean },
-          user_title: { type: :string, nullable: true },
+          user_title: { type: [:string, :null] },
           raw: { type: :string },
           actions_summary: {
             type: :array,
@@ -177,12 +177,12 @@ describe 'posts' do
           user_id: { type: :integer },
           hidden: { type: :boolean },
           trust_level: { type: :integer },
-          deleted_at: { type: :string, nullable: true },
+          deleted_at: { type: [:string, :null] },
           user_deleted: { type: :boolean },
-          edit_reason: { type: :string, nullable: true },
+          edit_reason: { type: [:string, :null] },
           can_view_edit_history: { type: :boolean },
           wiki: { type: :boolean },
-          reviewable_id: { type: :string, nullable: true },
+          reviewable_id: { type: [:string, :null] },
           reviewable_score_count: { type: :integer },
           reviewable_score_pending_count: { type: :integer },
         }
@@ -219,7 +219,7 @@ describe 'posts' do
             type: :object,
             properties: {
               id: { type: :integer },
-              name: { type: :string, nullable: true },
+              name: { type: [:string, :null] },
               username: { type: :string },
               avatar_template: { type: :string },
               created_at: { type: :string },
@@ -228,7 +228,7 @@ describe 'posts' do
               post_type: { type: :integer },
               updated_at: { type: :string },
               reply_count: { type: :integer },
-              reply_to_post_number: { type: :string, nullable: true },
+              reply_to_post_number: { type: [:string, :null] },
               quote_count: { type: :integer },
               incoming_link_count: { type: :integer },
               reads: { type: :integer },
@@ -237,17 +237,17 @@ describe 'posts' do
               yours: { type: :boolean },
               topic_id: { type: :integer },
               topic_slug: { type: :string },
-              display_username: { type: :string, nullable: true },
-              primary_group_name: { type: :string, nullable: true },
-              flair_url: { type: :string, nullable: true },
-              flair_bg_color: { type: :string, nullable: true },
-              flair_color: { type: :string, nullable: true },
+              display_username: { type: [:string, :null] },
+              primary_group_name: { type: [:string, :null] },
+              flair_url: { type: [:string, :null] },
+              flair_bg_color: { type: [:string, :null] },
+              flair_color: { type: [:string, :null] },
               version: { type: :integer },
               can_edit: { type: :boolean },
               can_delete: { type: :boolean },
               can_recover: { type: :boolean },
               can_wiki: { type: :boolean },
-              user_title: { type: :string, nullable: true },
+              user_title: { type: [:string, :null] },
               actions_summary: {
                 type: :array,
                 items: {
@@ -265,12 +265,12 @@ describe 'posts' do
               draft_sequence: { type: :integer },
               hidden: { type: :boolean },
               trust_level: { type: :integer },
-              deleted_at: { type: :string, nullable: true },
+              deleted_at: { type: [:string, :null] },
               user_deleted: { type: :boolean },
-              edit_reason: { type: :string, nullable: true },
+              edit_reason: { type: [:string, :null] },
               can_view_edit_history: { type: :boolean },
               wiki: { type: :boolean },
-              reviewable_id: { type: :string, nullable: true },
+              reviewable_id: { type: [:string, :null] },
               reviewable_score_count: { type: :integer },
               reviewable_score_pending_count: { type: :integer },
             }
@@ -350,7 +350,7 @@ describe 'posts' do
           post_type: { type: :integer },
           updated_at: { type: :string },
           reply_count: { type: :integer },
-          reply_to_post_number: { type: :string, nullable: true },
+          reply_to_post_number: { type: [:string, :null] },
           quote_count: { type: :integer },
           incoming_link_count: { type: :integer },
           reads: { type: :integer },
@@ -360,17 +360,17 @@ describe 'posts' do
           topic_id: { type: :integer },
           topic_slug: { type: :string },
           display_username: { type: :string },
-          primary_group_name: { type: :string, nullable: true },
-          flair_name: { type: :string, nullable: true },
-          flair_url: { type: :string, nullable: true },
-          flair_bg_color: { type: :string, nullable: true },
-          flair_color: { type: :string, nullable: true },
+          primary_group_name: { type: [:string, :null] },
+          flair_name: { type: [:string, :null] },
+          flair_url: { type: [:string, :null] },
+          flair_bg_color: { type: [:string, :null] },
+          flair_color: { type: [:string, :null] },
           version: { type: :integer },
           can_edit: { type: :boolean },
           can_delete: { type: :boolean },
           can_recover: { type: :boolean },
           can_wiki: { type: :boolean },
-          user_title: { type: :string, nullable: true },
+          user_title: { type: [:string, :null] },
           actions_summary: {
             type: :array,
             items: {
@@ -389,13 +389,13 @@ describe 'posts' do
           user_id: { type: :integer },
           hidden: { type: :boolean },
           trust_level: { type: :integer },
-          deleted_at: { type: :string, nullable: true },
+          deleted_at: { type: [:string, :null] },
           user_deleted: { type: :boolean },
-          edit_reason: { type: :string, nullable: true },
+          edit_reason: { type: [:string, :null] },
           can_view_edit_history: { type: :boolean },
           wiki: { type: :boolean },
           notice: { type: :object },
-          reviewable_id: { type: :string, nullable: true },
+          reviewable_id: { type: [:string, :null] },
           reviewable_score_count: { type: :integer },
           reviewable_score_pending_count: { type: :integer },
         }
diff --git a/spec/requests/api/private_messages_spec.rb b/spec/requests/api/private_messages_spec.rb
index 9bb3f6bef33..1e3f9a8c7af 100644
--- a/spec/requests/api/private_messages_spec.rb
+++ b/spec/requests/api/private_messages_spec.rb
@@ -40,7 +40,7 @@ describe 'private messages' do
             type: :object,
             properties: {
               can_create_topic: { type: :boolean },
-              draft: { type: :string, nullable: true },
+              draft: { type: [:string, :null] },
               draft_key: { type: :string },
               draft_sequence: { type: :integer },
               per_page: { type: :integer },
@@ -56,7 +56,7 @@ describe 'private messages' do
                     posts_count: { type: :integer },
                     reply_count: { type: :integer },
                     highest_post_number: { type: :integer },
-                    image_url: { type: :string, nullable: true },
+                    image_url: { type: [:string, :null] },
                     created_at: { type: :string },
                     last_posted_at: { type: :string },
                     bumped: { type: :boolean },
@@ -66,7 +66,7 @@ describe 'private messages' do
                     last_read_post_number: { type: :integer },
                     unread_posts: { type: :integer },
                     pinned: { type: :boolean },
-                    unpinned: { type: :string, nullable: true },
+                    unpinned: { type: [:string, :null] },
                     visible: { type: :boolean },
                     closed: { type: :boolean },
                     archived: { type: :boolean },
@@ -77,9 +77,9 @@ describe 'private messages' do
                     like_count: { type: :integer },
                     has_summary: { type: :boolean },
                     last_poster_username: { type: :string },
-                    category_id: { type: :string, nullable: true },
+                    category_id: { type: [:string, :null] },
                     pinned_globally: { type: :boolean },
-                    featured_link: { type: :string, nullable: true },
+                    featured_link: { type: [:string, :null] },
                     allowed_user_count: { type: :integer },
                     posters: {
                       type: :array,
@@ -89,7 +89,7 @@ describe 'private messages' do
                           extras: { type: :string },
                           description: { type: :string },
                           user_id: { type: :integer },
-                          primary_group_id: { type: :string, nullable: true },
+                          primary_group_id: { type: [:string, :null] },
                         }
                       },
                     },
@@ -99,9 +99,9 @@ describe 'private messages' do
                         type: :object,
                         properties: {
                           extras: { type: :string },
-                          description: { type: :string, nullable: true },
+                          description: { type: [:string, :null] },
                           user_id: { type: :integer },
-                          primary_group_id: { type: :string, nullable: true },
+                          primary_group_id: { type: [:string, :null] },
                         }
                       },
                     },
@@ -135,7 +135,7 @@ describe 'private messages' do
               properties: {
                 id: { type: :integer },
                 username: { type: :string },
-                name: { type: :string, nullable: true },
+                name: { type: [:string, :null] },
                 avatar_template: { type: :string },
               }
             },
@@ -149,7 +149,7 @@ describe 'private messages' do
             type: :object,
             properties: {
               can_create_topic: { type: :boolean },
-              draft: { type: :string, nullable: true },
+              draft: { type: [:string, :null] },
               draft_key: { type: :string },
               draft_sequence: { type: :integer },
               per_page: { type: :integer },
@@ -165,7 +165,7 @@ describe 'private messages' do
                     posts_count: { type: :integer },
                     reply_count: { type: :integer },
                     highest_post_number: { type: :integer },
-                    image_url: { type: :string, nullable: true },
+                    image_url: { type: [:string, :null] },
                     created_at: { type: :string },
                     last_posted_at: { type: :string },
                     bumped: { type: :boolean },
@@ -175,7 +175,7 @@ describe 'private messages' do
                     last_read_post_number: { type: :integer },
                     unread_posts: { type: :integer },
                     pinned: { type: :boolean },
-                    unpinned: { type: :string, nullable: true },
+                    unpinned: { type: [:string, :null] },
                     visible: { type: :boolean },
                     closed: { type: :boolean },
                     archived: { type: :boolean },
@@ -186,9 +186,9 @@ describe 'private messages' do
                     like_count: { type: :integer },
                     has_summary: { type: :boolean },
                     last_poster_username: { type: :string },
-                    category_id: { type: :string, nullable: true },
+                    category_id: { type: [:string, :null] },
                     pinned_globally: { type: :boolean },
-                    featured_link: { type: :string, nullable: true },
+                    featured_link: { type: [:string, :null] },
                     allowed_user_count: { type: :integer },
                     posters: {
                       type: :array,
@@ -198,7 +198,7 @@ describe 'private messages' do
                           extras: { type: :string },
                           description: { type: :string },
                           user_id: { type: :integer },
-                          primary_group_id: { type: :string, nullable: true },
+                          primary_group_id: { type: [:string, :null] },
                         }
                       },
                     },
diff --git a/spec/requests/api/schemas/json/admin_user_list_response.json b/spec/requests/api/schemas/json/admin_user_list_response.json
index 075318ac728..41e6e9705a0 100644
--- a/spec/requests/api/schemas/json/admin_user_list_response.json
+++ b/spec/requests/api/schemas/json/admin_user_list_response.json
@@ -48,13 +48,13 @@
         "type": "string"
       },
       "last_seen_age": {
-        "type": ""
+        "type": ["number", "null"]
       },
       "last_emailed_age": {
-        "type": ""
+        "type": ["number", "null"]
       },
       "created_at_age": {
-        "type": ""
+        "type": ["number", "null"]
       },
       "trust_level": {
         "type": "integer"
diff --git a/spec/requests/api/schemas/json/admin_user_response.json b/spec/requests/api/schemas/json/admin_user_response.json
index fdaa7dc52ca..4fdaba2bb02 100644
--- a/spec/requests/api/schemas/json/admin_user_response.json
+++ b/spec/requests/api/schemas/json/admin_user_response.json
@@ -39,13 +39,13 @@
       "type": "string"
     },
     "last_seen_age": {
-      "type": ""
+      "type": ["number", "null"]
     },
     "last_emailed_age": {
-      "type": ""
+      "type": ["number", "null"]
     },
     "created_at_age": {
-      "type": ""
+      "type": ["number", "null"]
     },
     "trust_level": {
       "type": "integer"
@@ -163,7 +163,7 @@
       "type": "integer"
     },
     "bounce_score": {
-      "type": ""
+      "type": ["integer", "null"]
     },
     "reset_bounce_score_after": {
       "type": ["string", "null"]
diff --git a/spec/requests/api/tags_spec.rb b/spec/requests/api/tags_spec.rb
index 47ec2cfbcdf..4bbfd7f5df0 100644
--- a/spec/requests/api/tags_spec.rb
+++ b/spec/requests/api/tags_spec.rb
@@ -190,7 +190,7 @@ describe 'tags' do
                 text: { type: :string },
                 count: { type: :integer },
                 pm_count: { type: :integer },
-                target_tag: { type: :string, nullable: true },
+                target_tag: { type: [:string, :null] },
               }
             },
           },
@@ -227,7 +227,7 @@ describe 'tags' do
               properties: {
                 id: { type: :integer },
                 username: { type: :string },
-                name: { type: :string, nullable: true },
+                name: { type: [:string, :null] },
                 avatar_template: { type: :string },
               }
             },
@@ -241,7 +241,7 @@ describe 'tags' do
             type: :object,
             properties: {
               can_create_topic: { type: :boolean },
-              draft: { type: :string, nullable: true },
+              draft: { type: [:string, :null] },
               draft_key: { type: :string },
               draft_sequence: { type: :integer },
               per_page: { type: :integer },
@@ -269,7 +269,7 @@ describe 'tags' do
                     posts_count: { type: :integer },
                     reply_count: { type: :integer },
                     highest_post_number: { type: :integer },
-                    image_url: { type: :string, nullable: true },
+                    image_url: { type: [:string, :null] },
                     created_at: { type: :string },
                     last_posted_at: { type: :string },
                     bumped: { type: :boolean },
@@ -279,7 +279,7 @@ describe 'tags' do
                     last_read_post_number: { type: :integer },
                     unread_posts: { type: :integer },
                     pinned: { type: :boolean },
-                    unpinned: { type: :string, nullable: true },
+                    unpinned: { type: [:string, :null] },
                     visible: { type: :boolean },
                     closed: { type: :boolean },
                     archived: { type: :boolean },
@@ -297,7 +297,7 @@ describe 'tags' do
                     last_poster_username: { type: :string },
                     category_id: { type: :integer },
                     pinned_globally: { type: :boolean },
-                    featured_link: { type: :string, nullable: true },
+                    featured_link: { type: [:string, :null] },
                     posters: {
                       type: :array,
                       items: {
@@ -306,7 +306,7 @@ describe 'tags' do
                           extras: { type: :string },
                           description: { type: :string },
                           user_id: { type: :integer },
-                          primary_group_id: { type: :string, nullable: true },
+                          primary_group_id: { type: [:string, :null] },
                         }
                       },
                     },
diff --git a/spec/requests/api/topics_spec.rb b/spec/requests/api/topics_spec.rb
index e7e0e18300e..0121fdf0406 100644
--- a/spec/requests/api/topics_spec.rb
+++ b/spec/requests/api/topics_spec.rb
@@ -33,7 +33,7 @@ describe 'topics' do
                   type: :object,
                   properties: {
                     id: { type: :integer },
-                    name: { type: :string, nullable: true },
+                    name: { type: [:string, :null] },
                     username: { type: :string },
                     avatar_template: { type: :string },
                     created_at: { type: :string },
@@ -42,7 +42,7 @@ describe 'topics' do
                     post_type: { type: :integer },
                     updated_at: { type: :string },
                     reply_count: { type: :integer },
-                    reply_to_post_number: { type: :string, nullable: true },
+                    reply_to_post_number: { type: [:string, :null] },
                     quote_count: { type: :integer },
                     incoming_link_count: { type: :integer },
                     reads: { type: :integer },
@@ -51,19 +51,19 @@ describe 'topics' do
                     yours: { type: :boolean },
                     topic_id: { type: :integer },
                     topic_slug: { type: :string },
-                    display_username: { type: :string, nullable: true },
-                    primary_group_name: { type: :string, nullable: true },
-                    flair_name: { type: :string, nullable: true },
-                    flair_url: { type: :string, nullable: true },
-                    flair_bg_color: { type: :string, nullable: true },
-                    flair_color: { type: :string, nullable: true },
+                    display_username: { type: [:string, :null] },
+                    primary_group_name: { type: [:string, :null] },
+                    flair_name: { type: [:string, :null] },
+                    flair_url: { type: [:string, :null] },
+                    flair_bg_color: { type: [:string, :null] },
+                    flair_color: { type: [:string, :null] },
                     version: { type: :integer },
                     can_edit: { type: :boolean },
                     can_delete: { type: :boolean },
                     can_recover: { type: :boolean },
                     can_wiki: { type: :boolean },
                     read: { type: :boolean },
-                    user_title: { type: :string, nullable: true },
+                    user_title: { type: [:string, :null] },
                     actions_summary: {
                       type: :array,
                       items: {
@@ -80,9 +80,9 @@ describe 'topics' do
                     user_id: { type: :integer },
                     hidden: { type: :boolean },
                     trust_level: { type: :integer },
-                    deleted_at: { type: :string, nullable: true },
+                    deleted_at: { type: [:string, :null] },
                     user_deleted: { type: :boolean },
-                    edit_reason: { type: :string, nullable: true },
+                    edit_reason: { type: [:string, :null] },
                     can_view_edit_history: { type: :boolean },
                     wiki: { type: :boolean },
                     reviewable_id: { type: :integer },
@@ -134,7 +134,7 @@ describe 'topics' do
                     post_type: { type: :integer },
                     updated_at: { type: :string },
                     reply_count: { type: :integer },
-                    reply_to_post_number: { type: :string, nullable: true },
+                    reply_to_post_number: { type: [:string, :null] },
                     quote_count: { type: :integer },
                     incoming_link_count: { type: :integer },
                     reads: { type: :integer },
@@ -144,11 +144,11 @@ describe 'topics' do
                     topic_id: { type: :integer },
                     topic_slug: { type: :string },
                     display_username: { type: :string },
-                    primary_group_name: { type: :string, nullable: true },
-                    flair_name: { type: :string, nullable: true },
-                    flair_url: { type: :string, nullable: true },
-                    flair_bg_color: { type: :string, nullable: true },
-                    flair_color: { type: :string, nullable: true },
+                    primary_group_name: { type: [:string, :null] },
+                    flair_name: { type: [:string, :null] },
+                    flair_url: { type: [:string, :null] },
+                    flair_bg_color: { type: [:string, :null] },
+                    flair_color: { type: [:string, :null] },
                     version: { type: :integer },
                     can_edit: { type: :boolean },
                     can_delete: { type: :boolean },
@@ -167,7 +167,7 @@ describe 'topics' do
                       },
                     },
                     read: { type: :boolean },
-                    user_title: { type: :string, nullable: true },
+                    user_title: { type: [:string, :null] },
                     actions_summary: {
                       type: :array,
                       items: {
@@ -184,9 +184,9 @@ describe 'topics' do
                     user_id: { type: :integer },
                     hidden: { type: :boolean },
                     trust_level: { type: :integer },
-                    deleted_at: { type: :string, nullable: true },
+                    deleted_at: { type: [:string, :null] },
                     user_deleted: { type: :boolean },
-                    edit_reason: { type: :string, nullable: true },
+                    edit_reason: { type: [:string, :null] },
                     can_view_edit_history: { type: :boolean },
                     wiki: { type: :boolean },
                     reviewable_id: { type: :integer },
@@ -219,9 +219,9 @@ describe 'topics' do
                 posts_count: { type: :integer },
                 reply_count: { type: :integer },
                 highest_post_number: { type: :integer },
-                image_url: { type: :string, nullable: true },
+                image_url: { type: [:string, :null] },
                 created_at: { type: :string },
-                last_posted_at: { type: :string, nullable: true },
+                last_posted_at: { type: [:string, :null] },
                 bumped: { type: :boolean },
                 bumped_at: { type: :string },
                 archetype: { type: :string },
@@ -239,13 +239,13 @@ describe 'topics' do
                 like_count: { type: :integer },
                 views: { type: :integer },
                 category_id: { type: :integer },
-                featured_link: { type: :string, nullable: true },
+                featured_link: { type: [:string, :null] },
                 posters: {
                   type: :array,
                   items: {
                     type: :object,
                     properties: {
-                      extras: { type: :string, nullable: true },
+                      extras: { type: [:string, :null] },
                       description: { type: :string },
                       user: {
                         type: :object,
@@ -270,7 +270,7 @@ describe 'topics' do
           views: { type: :integer },
           reply_count: { type: :integer },
           like_count: { type: :integer },
-          last_posted_at: { type: :string, nullable: true },
+          last_posted_at: { type: [:string, :null] },
           visible: { type: :boolean },
           closed: { type: :boolean },
           archived: { type: :boolean },
@@ -278,22 +278,22 @@ describe 'topics' do
           archetype: { type: :string },
           slug: { type: :string },
           category_id: { type: :integer },
-          word_count: { type: :integer, nullable: true },
-          deleted_at: { type: :string, nullable: true },
+          word_count: { type: [:integer, :null] },
+          deleted_at: { type: [:string, :null] },
           user_id: { type: :integer },
-          featured_link: { type: :string, nullable: true },
+          featured_link: { type: [:string, :null] },
           pinned_globally: { type: :boolean },
-          pinned_at: { type: :string, nullable: true },
-          pinned_until: { type: :string, nullable: true },
-          image_url: { type: :string, nullable: true },
-          draft: { type: :string, nullable: true },
+          pinned_at: { type: [:string, :null] },
+          pinned_until: { type: [:string, :null] },
+          image_url: { type: [:string, :null] },
+          draft: { type: [:string, :null] },
           draft_key: { type: :string },
           draft_sequence: { type: :integer },
-          unpinned: { type: :string, nullable: true },
+          unpinned: { type: [:string, :null] },
           pinned: { type: :boolean },
           current_post_number: { type: :integer },
-          highest_post_number: { type: :integer, nullable: true },
-          deleted_by: { type: :string, nullable: true },
+          highest_post_number: { type: [:integer, :null] },
+          deleted_by: { type: [:string, :null] },
           has_deleted: { type: :boolean },
           actions_summary: {
             type: :array,
@@ -309,11 +309,11 @@ describe 'topics' do
           },
           chunk_size: { type: :integer },
           bookmarked: { type: :boolean },
-          topic_timer: { type: :string, nullable: true },
+          topic_timer: { type: [:string, :null] },
           message_bus_last_id: { type: :integer },
           participant_count: { type: :integer },
           show_read_indicator: { type: :boolean },
-          thumbnails: { type: :string, nullable: true },
+          thumbnails: { type: [:string, :null] },
           details: {
             type: :object,
             properties: {
@@ -338,11 +338,11 @@ describe 'topics' do
                     name: { type: :string },
                     avatar_template: { type: :string },
                     post_count: { type: :integer },
-                    primary_group_name: { type: :string, nullable: true },
-                    flair_name: { type: :string, nullable: true },
-                    flair_url: { type: :string, nullable: true },
-                    flair_color: { type: :string, nullable: true },
-                    flair_bg_color: { type: :string, nullable: true },
+                    primary_group_name: { type: [:string, :null] },
+                    flair_name: { type: [:string, :null] },
+                    flair_url: { type: [:string, :null] },
+                    flair_color: { type: [:string, :null] },
+                    flair_bg_color: { type: [:string, :null] },
                   }
                 },
               },
@@ -529,7 +529,7 @@ describe 'topics' do
       response '200', 'topic updated' do
         schema type: :object, properties: {
           success: { type: :string, example: "OK" },
-          topic_status_update: { type: :string, nullable: true },
+          topic_status_update: { type: [:string, :null] },
         }
 
         let(:request_body) { { status: 'closed', enabled: 'true' } }
@@ -567,7 +567,7 @@ describe 'topics' do
               properties: {
                 id: { type: :integer },
                 username: { type: :string },
-                name: { type: :string, nullable: true },
+                name: { type: [:string, :null] },
                 avatar_template: { type: :string },
               }
             },
@@ -581,7 +581,7 @@ describe 'topics' do
             type: :object,
             properties: {
               can_create_topic: { type: :boolean },
-              draft: { type: :string, nullable: true },
+              draft: { type: [:string, :null] },
               draft_key: { type: :string },
               draft_sequence: { type: :integer },
               per_page: { type: :integer },
@@ -607,7 +607,7 @@ describe 'topics' do
                     last_read_post_number: { type: :integer },
                     unread_posts: { type: :integer },
                     pinned: { type: :boolean },
-                    unpinned: { type: :string, nullable: true },
+                    unpinned: { type: [:string, :null] },
                     visible: { type: :boolean },
                     closed: { type: :boolean },
                     archived: { type: :boolean },
@@ -621,7 +621,7 @@ describe 'topics' do
                     category_id: { type: :integer },
                     op_like_count: { type: :integer },
                     pinned_globally: { type: :boolean },
-                    featured_link: { type: :string, nullable: true },
+                    featured_link: { type: [:string, :null] },
                     posters: {
                       type: :array,
                       items: {
@@ -630,7 +630,7 @@ describe 'topics' do
                           extras: { type: :string },
                           description: { type: :string },
                           user_id: { type: :integer },
-                          primary_group_id: { type: :string, nullable: true },
+                          primary_group_id: { type: [:string, :null] },
                         }
                       },
                     },
@@ -680,7 +680,7 @@ describe 'topics' do
             type: :object,
             properties: {
               can_create_topic: { type: :boolean },
-              draft: { type: :string, nullable: true },
+              draft: { type: [:string, :null] },
               draft_key: { type: :string },
               draft_sequence: { type: :integer },
               for_period: { type: :string },
@@ -697,7 +697,7 @@ describe 'topics' do
                     posts_count: { type: :integer },
                     reply_count: { type: :integer },
                     highest_post_number: { type: :integer },
-                    image_url: { type: :string, nullable: true },
+                    image_url: { type: [:string, :null] },
                     created_at: { type: :string },
                     last_posted_at: { type: :string },
                     bumped: { type: :boolean },
@@ -721,16 +721,16 @@ describe 'topics' do
                     category_id: { type: :integer },
                     op_like_count: { type: :integer },
                     pinned_globally: { type: :boolean },
-                    featured_link: { type: :string, nullable: true },
+                    featured_link: { type: [:string, :null] },
                     posters: {
                       type: :array,
                       items: {
                         type: :object,
                         properties: {
-                          extras: { type: :string, nullable: true },
+                          extras: { type: [:string, :null] },
                           description: { type: :string },
                           user_id: { type: :integer },
-                          primary_group_id: { type: :string, nullable: true },
+                          primary_group_id: { type: [:string, :null] },
                         }
                       },
                     },
@@ -782,7 +782,7 @@ describe 'topics' do
             type: :object,
             properties: {
               can_create_topic: { type: :boolean },
-              draft: { type: :string, nullable: true },
+              draft: { type: [:string, :null] },
               draft_key: { type: :string },
               draft_sequence: { type: :integer },
               for_period: { type: :string },
@@ -799,7 +799,7 @@ describe 'topics' do
                     posts_count: { type: :integer },
                     reply_count: { type: :integer },
                     highest_post_number: { type: :integer },
-                    image_url: { type: :string, nullable: true },
+                    image_url: { type: [:string, :null] },
                     created_at: { type: :string },
                     last_posted_at: { type: :string },
                     bumped: { type: :boolean },
@@ -823,16 +823,16 @@ describe 'topics' do
                     category_id: { type: :integer },
                     op_like_count: { type: :integer },
                     pinned_globally: { type: :boolean },
-                    featured_link: { type: :string, nullable: true },
+                    featured_link: { type: [:string, :null] },
                     posters: {
                       type: :array,
                       items: {
                         type: :object,
                         properties: {
-                          extras: { type: :string, nullable: true },
+                          extras: { type: [:string, :null] },
                           description: { type: :string },
                           user_id: { type: :integer },
-                          primary_group_id: { type: :string, nullable: true },
+                          primary_group_id: { type: [:string, :null] },
                         }
                       },
                     },
@@ -947,10 +947,10 @@ describe 'topics' do
         schema type: :object, properties: {
           success: { type: :string, example: "OK" },
           execute_at: { type: :string },
-          duration: { type: :string, nullable: true },
+          duration: { type: [:string, :null] },
           based_on_last_post: { type: :boolean },
           closed: { type: :boolean },
-          category_id: { type: :string, nullable: true },
+          category_id: { type: [:string, :null] },
         }
 
         let(:request_body) { { time: Time.current + 1.day, status_type: 'close' } }
diff --git a/spec/swagger_helper.rb b/spec/swagger_helper.rb
index 5a6638f14cb..13821cde957 100644
--- a/spec/swagger_helper.rb
+++ b/spec/swagger_helper.rb
@@ -125,8 +125,8 @@ RSpec.configure do |config|
                   username: { type: :string },
                   name: { type: :string },
                   avatar_template: { type: :string },
-                  last_posted_at: { type: :string, nullable: true },
-                  last_seen_at: { type: :string, nullable: true },
+                  last_posted_at: { type: [:string, :null] },
+                  last_seen_at: { type: [:string, :null] },
                   created_at: { type: :string },
                   ignored: { type: :boolean },
                   muted: { type: :boolean },
@@ -137,7 +137,7 @@ RSpec.configure do |config|
                   trust_level: { type: :integer },
                   moderator: { type: :boolean },
                   admin: { type: :boolean },
-                  title: { type: :string, nullable: true },
+                  title: { type: [:string, :null] },
                   badge_count: { type: :integer },
                   user_fields: {
                     type: :object,
@@ -151,18 +151,18 @@ RSpec.configure do |config|
                   },
                   time_read: { type: :integer },
                   recent_time_read: { type: :integer },
-                  primary_group_id: { type: :string, nullable: true },
-                  primary_group_name: { type: :string, nullable: true },
-                  flair_url: { type: :string, nullable: true },
-                  flair_bg_color: { type: :string, nullable: true },
-                  flair_color: { type: :string, nullable: true },
-                  featured_topic: { type: :string, nullable: true },
+                  primary_group_id: { type: [:string, :null] },
+                  primary_group_name: { type: [:string, :null] },
+                  flair_url: { type: [:string, :null] },
+                  flair_bg_color: { type: [:string, :null] },
+                  flair_color: { type: [:string, :null] },
+                  featured_topic: { type: [:string, :null] },
                   staged: { type: :boolean },
                   can_edit: { type: :boolean },
                   can_edit_username: { type: :boolean },
                   can_edit_email: { type: :boolean },
                   can_edit_name: { type: :boolean },
-                  uploaded_avatar_id: { type: :string, nullable: true },
+                  uploaded_avatar_id: { type: [:string, :null] },
                   has_title_badges: { type: :boolean },
                   pending_count: { type: :integer },
                   profile_view_count: { type: :integer },
@@ -172,7 +172,7 @@ RSpec.configure do |config|
                   post_count: { type: :integer },
                   can_be_deleted: { type: :boolean },
                   can_delete_all_posts: { type: :boolean },
-                  locale: { type: :string, nullable: true },
+                  locale: { type: [:string, :null] },
                   muted_category_ids: {
                     type: :array,
                     items: {
@@ -218,7 +218,7 @@ RSpec.configure do |config|
                     items: {
                     },
                   },
-                  system_avatar_upload_id: { type: :string, nullable: true },
+                  system_avatar_upload_id: { type: [:string, :null] },
                   system_avatar_template: { type: :string },
                   muted_usernames: {
                     type: :array,
@@ -239,7 +239,7 @@ RSpec.configure do |config|
                   can_change_bio: { type: :boolean },
                   can_change_location: { type: :boolean },
                   can_change_website: { type: :boolean },
-                  user_api_keys: { type: :string, nullable: true },
+                  user_api_keys: { type: [:string, :null] },
                   user_auth_tokens: {
                     type: :array,
                     items: {
@@ -263,7 +263,7 @@ RSpec.configure do |config|
                     items: {
                     },
                   },
-                  invited_by: { type: :string, nullable: true },
+                  invited_by: { type: [:string, :null] },
                   groups: {
                     type: :array,
                     items: {
@@ -278,22 +278,22 @@ RSpec.configure do |config|
                         messageable_level: { type: :integer },
                         visibility_level: { type: :integer },
                         primary_group: { type: :boolean },
-                        title: { type: :string, nullable: true },
-                        grant_trust_level: { type: :string, nullable: true },
-                        incoming_email: { type: :string, nullable: true },
+                        title: { type: [:string, :null] },
+                        grant_trust_level: { type: [:string, :null] },
+                        incoming_email: { type: [:string, :null] },
                         has_messages: { type: :boolean },
-                        flair_url: { type: :string, nullable: true },
-                        flair_bg_color: { type: :string, nullable: true },
-                        flair_color: { type: :string, nullable: true },
-                        bio_raw: { type: :string, nullable: true },
-                        bio_cooked: { type: :string, nullable: true },
-                        bio_excerpt: { type: :string, nullable: true },
+                        flair_url: { type: [:string, :null] },
+                        flair_bg_color: { type: [:string, :null] },
+                        flair_color: { type: [:string, :null] },
+                        bio_raw: { type: [:string, :null] },
+                        bio_cooked: { type: [:string, :null] },
+                        bio_excerpt: { type: [:string, :null] },
                         public_admission: { type: :boolean },
                         public_exit: { type: :boolean },
                         allow_membership_requests: { type: :boolean },
-                        full_name: { type: :string, nullable: true },
+                        full_name: { type: [:string, :null] },
                         default_notification_level: { type: :integer },
-                        membership_request_template: { type: :string, nullable: true },
+                        membership_request_template: { type: [:string, :null] },
                         members_visibility_level: { type: :integer },
                         can_see_members: { type: :boolean },
                         can_admin_group: { type: :boolean },
@@ -322,8 +322,8 @@ RSpec.configure do |config|
                       email_level: { type: :integer },
                       email_messages_level: { type: :integer },
                       external_links_in_new_tab: { type: :boolean },
-                      color_scheme_id: { type: :string, nullable: true },
-                      dark_scheme_id: { type: :string, nullable: true },
+                      color_scheme_id: { type: [:string, :null] },
+                      dark_scheme_id: { type: [:string, :null] },
                       dynamic_favicon: { type: :boolean },
                       enable_quoting: { type: :boolean },
                       enable_defer: { type: :boolean },
@@ -344,12 +344,12 @@ RSpec.configure do |config|
                       theme_key_seq: { type: :integer },
                       allow_private_messages: { type: :boolean },
                       enable_allowed_pm_users: { type: :boolean },
-                      homepage_id: { type: :string, nullable: true },
+                      homepage_id: { type: [:string, :null] },
                       hide_profile_and_presence: { type: :boolean },
                       text_size: { type: :string },
                       text_size_seq: { type: :integer },
                       title_count_mode: { type: :string },
-                      timezone: { type: :string, nullable: true },
+                      timezone: { type: [:string, :null] },
                       skip_new_user_tips: { type: :boolean },
                     }
                   },