/usr/lib/ruby/vendor_ruby/ is in ruby-activemodel 2:4.2.10-0ubuntu4.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/active_model/
/usr/lib/ruby/vendor_ruby/active_model/attribute_methods.rb
/usr/lib/ruby/vendor_ruby/active_model/callbacks.rb
/usr/lib/ruby/vendor_ruby/active_model/conversion.rb
/usr/lib/ruby/vendor_ruby/active_model/dirty.rb
/usr/lib/ruby/vendor_ruby/active_model/errors.rb
/usr/lib/ruby/vendor_ruby/active_model/forbidden_attributes_protection.rb
/usr/lib/ruby/vendor_ruby/active_model/gem_version.rb
/usr/lib/ruby/vendor_ruby/active_model/lint.rb
/usr/lib/ruby/vendor_ruby/active_model/locale/
/usr/lib/ruby/vendor_ruby/active_model/locale/en.yml
/usr/lib/ruby/vendor_ruby/active_model/model.rb
/usr/lib/ruby/vendor_ruby/active_model/naming.rb
/usr/lib/ruby/vendor_ruby/active_model/railtie.rb
/usr/lib/ruby/vendor_ruby/active_model/secure_password.rb
/usr/lib/ruby/vendor_ruby/active_model/serialization.rb
/usr/lib/ruby/vendor_ruby/active_model/serializers/
/usr/lib/ruby/vendor_ruby/active_model/serializers/json.rb
/usr/lib/ruby/vendor_ruby/active_model/serializers/xml.rb
/usr/lib/ruby/vendor_ruby/active_model/test_case.rb
/usr/lib/ruby/vendor_ruby/active_model/translation.rb
/usr/lib/ruby/vendor_ruby/active_model/validations/
/usr/lib/ruby/vendor_ruby/active_model/validations/absence.rb
/usr/lib/ruby/vendor_ruby/active_model/validations/acceptance.rb
/usr/lib/ruby/vendor_ruby/active_model/validations/callbacks.rb
/usr/lib/ruby/vendor_ruby/active_model/validations/clusivity.rb
/usr/lib/ruby/vendor_ruby/active_model/validations/confirmation.rb
/usr/lib/ruby/vendor_ruby/active_model/validations/exclusion.rb
/usr/lib/ruby/vendor_ruby/active_model/validations/format.rb
/usr/lib/ruby/vendor_ruby/active_model/validations/inclusion.rb
/usr/lib/ruby/vendor_ruby/active_model/validations/length.rb
/usr/lib/ruby/vendor_ruby/active_model/validations/numericality.rb
/usr/lib/ruby/vendor_ruby/active_model/validations/presence.rb
/usr/lib/ruby/vendor_ruby/active_model/validations/validates.rb
/usr/lib/ruby/vendor_ruby/active_model/validations/with.rb
/usr/lib/ruby/vendor_ruby/active_model/validations.rb
/usr/lib/ruby/vendor_ruby/active_model/validator.rb
/usr/lib/ruby/vendor_ruby/active_model/version.rb
/usr/lib/ruby/vendor_ruby/active_model.rb