code: function getCustomComponentTags(config) {
      let {usingComponents} = config || {};
      if (!usingComponents) {
          return;
      }
  
      return Object.keys(usingComponents).map(k => toHyphen(k));
  }
docs: Get custom component tags
  
  @inner
  @param {Object} config the component config
  @return {?Array.<string>}