/usr/lib/ruby/vendor_ruby/ is in ruby-activejob 2:4.2.10-0ubuntu4.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/active_job/
/usr/lib/ruby/vendor_ruby/active_job/arguments.rb
/usr/lib/ruby/vendor_ruby/active_job/base.rb
/usr/lib/ruby/vendor_ruby/active_job/callbacks.rb
/usr/lib/ruby/vendor_ruby/active_job/configured_job.rb
/usr/lib/ruby/vendor_ruby/active_job/core.rb
/usr/lib/ruby/vendor_ruby/active_job/enqueuing.rb
/usr/lib/ruby/vendor_ruby/active_job/execution.rb
/usr/lib/ruby/vendor_ruby/active_job/gem_version.rb
/usr/lib/ruby/vendor_ruby/active_job/logging.rb
/usr/lib/ruby/vendor_ruby/active_job/queue_adapter.rb
/usr/lib/ruby/vendor_ruby/active_job/queue_adapters/
/usr/lib/ruby/vendor_ruby/active_job/queue_adapters/backburner_adapter.rb
/usr/lib/ruby/vendor_ruby/active_job/version.rb
/usr/lib/ruby/vendor_ruby/active_job/queue_adapters/delayed_job_adapter.rb
/usr/lib/ruby/vendor_ruby/active_job/queue_adapters/inline_adapter.rb
/usr/lib/ruby/vendor_ruby/active_job/queue_adapters/qu_adapter.rb
/usr/lib/ruby/vendor_ruby/active_job/queue_adapters/que_adapter.rb
/usr/lib/ruby/vendor_ruby/active_job/queue_adapters/queue_classic_adapter.rb
/usr/lib/ruby/vendor_ruby/active_job/queue_adapters/resque_adapter.rb
/usr/lib/ruby/vendor_ruby/active_job/queue_adapters/sidekiq_adapter.rb
/usr/lib/ruby/vendor_ruby/active_job/queue_adapters/sneakers_adapter.rb
/usr/lib/ruby/vendor_ruby/active_job/queue_adapters/sucker_punch_adapter.rb
/usr/lib/ruby/vendor_ruby/active_job/queue_adapters/test_adapter.rb
/usr/lib/ruby/vendor_ruby/active_job/queue_adapters.rb
/usr/lib/ruby/vendor_ruby/active_job/queue_name.rb
/usr/lib/ruby/vendor_ruby/active_job/railtie.rb
/usr/lib/ruby/vendor_ruby/active_job/test_case.rb
/usr/lib/ruby/vendor_ruby/active_job/test_helper.rb
/usr/lib/ruby/vendor_ruby/active_job/translation.rb
/usr/lib/ruby/vendor_ruby/active_job.rb
/usr/lib/ruby/vendor_ruby/rails/
/usr/lib/ruby/vendor_ruby/rails/generators/
/usr/lib/ruby/vendor_ruby/rails/generators/job/
/usr/lib/ruby/vendor_ruby/rails/generators/job/job_generator.rb
/usr/lib/ruby/vendor_ruby/rails/generators/job/templates/
/usr/lib/ruby/vendor_ruby/rails/generators/job/templates/job.rb