docs: function(attrs) {
      if (attrs.authentication !== 'KERBEROS') {
        if (attrs.kerberos_service_name) {
          throw new TypeError(format(
            'The kerberos_service_name field does not apply when '
            + 'using %s for authentication.', attrs.authentication));
        }
        if (attrs.kerberos_principal) {
          throw new TypeError(format(
            'The kerberos_principal field does not apply when '
            + 'using %s for authentication.', attrs.authentication));
        }
        if (attrs.kerberos_password) {
          throw new TypeError(format(
            'The kerberos_password field does not apply when '
            + 'using %s for authentication.', attrs.authentication));
        }
      }
  
      if (attrs.authentication === 'KERBEROS') {
        if (!attrs.kerberos_principal) {
          throw new TypeError(format(
            'The kerberos_principal field is required when '
            + 'using KERBEROS for authentication.'));
        }
      }
    }