code: def validate_headers_for_server(credentials)
        application_name = credentials[:application_name]
        if (application_name.nil? or application_name.empty? or
            application_name.include?(DEFAULT_APPLICATION_NAME) or
            application_name.include?(LEGACY_DEFAULT_APPLICATION_NAME))
          raise AdsCommon::Errors::AuthError, (
              'Application name must be specified and cannot be the default')
        end
        return nil
      end
docs: Validates that the right credentials are being used for the chosen
   environment.