code: function verifyClientIdentifiers (req, res, next) {
    // mismatching client identifiers
    if (req.token.payload.sub !== req.params.clientId) {
      return next(new AuthorizationError({
        error: 'unauthorized_client',
        error_description: 'Mismatching client id',
        statusCode: 403
      }))
  
    // all's well
    } else {
      next()
    }
  }
docs: Verify Client Params