Incompatibility with Faker gem

## To Reproduce

Run below code. It depends on an order of gem. Put faker-okinawa after faker like this.

```
require "bundler/inline"

gemfile(true) do
  source "https://rubygems.org"

  git_source(:github) { |repo| "https://github.com/#{repo}.git" }

  gem "faker",         "2.18.0"
  gem "faker-okinawa", "0.1.1"      
end
```