class Google::Auth::ExternalAccount::IdentityPoolCredentials

def retrieve_subject_token!
  content, resource_name = token_data
  if @credential_source_format_type == "text"
    token = content
  else
    begin
      response_data = MultiJson.load content, symbolize_keys: true
      token = response_data[@credential_source_field_name.to_sym]
    rescue StandardError
      raise "Unable to parse subject_token from JSON resource #{resource_name} " \
            "using key #{@credential_source_field_name}"
    end
  end
  raise "Missing subject_token in the credential_source file/response." unless token
  token
end