/usr/lib/ is in ruby-jbuilder 2.3.1-2.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/generators/
/usr/lib/ruby/vendor_ruby/generators/rails/
/usr/lib/ruby/vendor_ruby/generators/rails/jbuilder_generator.rb
/usr/lib/ruby/vendor_ruby/generators/rails/scaffold_controller_generator.rb
/usr/lib/ruby/vendor_ruby/generators/rails/templates/
/usr/lib/ruby/vendor_ruby/generators/rails/templates/api_controller.rb
/usr/lib/ruby/vendor_ruby/generators/rails/templates/controller.rb
/usr/lib/ruby/vendor_ruby/generators/rails/templates/index.json.jbuilder
/usr/lib/ruby/vendor_ruby/generators/rails/templates/show.json.jbuilder
/usr/lib/ruby/vendor_ruby/jbuilder/
/usr/lib/ruby/vendor_ruby/jbuilder/blank.rb
/usr/lib/ruby/vendor_ruby/jbuilder/dependency_tracker.rb
/usr/lib/ruby/vendor_ruby/jbuilder/errors.rb
/usr/lib/ruby/vendor_ruby/jbuilder/jbuilder.rb
/usr/lib/ruby/vendor_ruby/jbuilder/jbuilder_template.rb
/usr/lib/ruby/vendor_ruby/jbuilder/key_formatter.rb
/usr/lib/ruby/vendor_ruby/jbuilder/railtie.rb
/usr/lib/ruby/vendor_ruby/jbuilder.rb