activerecord/lib/active_record/connection_adapters/postgresql/column.rb
- usage added in 64fd666e
- unneeded because of active_support/rails: 8f58d6e5

railties/lib/rails/rack/logger.rb
- usage added in c83d9a11
- usage removed in c131211c

activesupport/lib/active_support/number_helper/number_converter.rb
- the NumberHelper was split into multiple classes in 2da9d67c, however
  the require was left in NumberConverter even though
  NumberToPhoneConverter is the only class where it's used

activesupport/lib/active_support/duration/iso8601_serializer.rb
- usage added in 04c512da
- usage removed in 51e991f0