text: const setAudiences = require('./mixins/set_audiences');
  const hasFormat = require('./mixins/has_format');
  const isSenderConstrained = require('./mixins/is_sender_constrained');
  const apply = require('./mixins/apply');
  
  module.exports = provider => class ClientCredentials extends apply([
    setAudiences,
    isSenderConstrained,
    hasFormat(provider, 'ClientCredentials', provider.BaseToken),
  ]) {
    static get IN_PAYLOAD() {
      return [
        ...super.IN_PAYLOAD,
        'aud',
        'extra',
        'scope',
      ];
    }
  };
  