Gem::ConfigFile#set_api_key

# File tmp/rubies/ruby-4.1.0-preview1/lib/rubygems/config_file.rb, line 481
def set_api_key(host, api_key)
  if credential_store && host != :rubygems_api_key
    store = active_credential_store

    if api_key.to_s.empty?
      delete_stored_key(store, host)
    elsif store&.set(self.class.credential_store_account(host), api_key)
      remove_api_key_from_file(host)
      return
    else
      delete_stored_key(store, host)
      warn_credential_store_fallback
    end
  end

  check_credentials_permissions

  config = load_file(credentials_path).merge(self.class.normalize_credentials_key(host) => api_key)

  write_credentials(config)

  load_api_keys # reload
end