Add feature flag to pagination params

config/feature_flags/development/only_positive_pagination_values.yml

+---
+name: only_positive_pagination_values
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/93571
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/369225
+milestone: '15.3'
+type: development
+group: group::source code
+default_enabled: false

lib/api/pagination_params.rb

@@ -17,7 +17,9 @@ module PaginationParams
     included do
       helpers do
         params :pagination do
-          with(type: Integer, values: ->(v) { !v.is_a?(Integer) || v > 0 }) do
+          with(type: Integer, values: ->(v) do
+            !v.is_a?(Integer) || Feature.disabled?(:only_positive_pagination_values) || v > 0
+          end) do
             optional :page, default: 1, desc: 'Current page number'
             optional :per_page, default: 20, desc: 'Number of items per page'
           end