/usr/lib/ruby/ is in ruby-sidekiq 4.0.1+dfsg-2.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/generators/
/usr/lib/ruby/vendor_ruby/generators/sidekiq/
/usr/lib/ruby/vendor_ruby/generators/sidekiq/worker_generator.rb
/usr/lib/ruby/vendor_ruby/generators/sidekiq/templates/
/usr/lib/ruby/vendor_ruby/generators/sidekiq/templates/worker_test.rb.erb
/usr/lib/ruby/vendor_ruby/generators/sidekiq/templates/worker_spec.rb.erb
/usr/lib/ruby/vendor_ruby/generators/sidekiq/templates/worker.rb.erb
/usr/lib/ruby/vendor_ruby/sidekiq.rb
/usr/lib/ruby/vendor_ruby/sidekiq/
/usr/lib/ruby/vendor_ruby/sidekiq/web.rb
/usr/lib/ruby/vendor_ruby/sidekiq/rails.rb
/usr/lib/ruby/vendor_ruby/sidekiq/redis_connection.rb
/usr/lib/ruby/vendor_ruby/sidekiq/api.rb
/usr/lib/ruby/vendor_ruby/sidekiq/testing.rb
/usr/lib/ruby/vendor_ruby/sidekiq/launcher.rb
/usr/lib/ruby/vendor_ruby/sidekiq/extensions/
/usr/lib/ruby/vendor_ruby/sidekiq/extensions/action_mailer.rb
/usr/lib/ruby/vendor_ruby/sidekiq/extensions/active_record.rb
/usr/lib/ruby/vendor_ruby/sidekiq/extensions/class_methods.rb
/usr/lib/ruby/vendor_ruby/sidekiq/extensions/generic_proxy.rb
/usr/lib/ruby/vendor_ruby/sidekiq/worker.rb
/usr/lib/ruby/vendor_ruby/sidekiq/util.rb
/usr/lib/ruby/vendor_ruby/sidekiq/manager.rb
/usr/lib/ruby/vendor_ruby/sidekiq/scheduled.rb
/usr/lib/ruby/vendor_ruby/sidekiq/cli.rb
/usr/lib/ruby/vendor_ruby/sidekiq/core_ext.rb
/usr/lib/ruby/vendor_ruby/sidekiq/fetch.rb
/usr/lib/ruby/vendor_ruby/sidekiq/logging.rb
/usr/lib/ruby/vendor_ruby/sidekiq/client.rb
/usr/lib/ruby/vendor_ruby/sidekiq/exception_handler.rb
/usr/lib/ruby/vendor_ruby/sidekiq/middleware/
/usr/lib/ruby/vendor_ruby/sidekiq/middleware/server/
/usr/lib/ruby/vendor_ruby/sidekiq/middleware/server/active_record.rb
/usr/lib/ruby/vendor_ruby/sidekiq/middleware/server/retry_jobs.rb
/usr/lib/ruby/vendor_ruby/sidekiq/middleware/server/logging.rb
/usr/lib/ruby/vendor_ruby/sidekiq/middleware/chain.rb
/usr/lib/ruby/vendor_ruby/sidekiq/middleware/i18n.rb
/usr/lib/ruby/vendor_ruby/sidekiq/processor.rb
/usr/lib/ruby/vendor_ruby/sidekiq/web_helpers.rb
/usr/lib/ruby/vendor_ruby/sidekiq/paginator.rb
/usr/lib/ruby/vendor_ruby/sidekiq/version.rb
/usr/lib/ruby/vendor_ruby/sidekiq/testing/
/usr/lib/ruby/vendor_ruby/sidekiq/testing/inline.rb