$urlRouterProvider.otherwise状态重新加载时父级的状态参数为空

$stateProvider.state('parentState', {
  url: '/parent/:param',
  resolve: {
    paramValue: ['$stateParams', function($stateParams) {
      return $stateParams.param;
    }]
  }
});

$stateProvider.state('parentState.childState', {
  url: '/child',
  controller: 'ChildController',
  resolve: {
    parentParam: ['paramValue', function(paramValue) {
      return paramValue;
    }]
  }
});

$stateProvider.state('parentState', {
  url: '/parent',
  params: {
    param: null
  },
  controller: 'ParentController'
});

$stateProvider.state('parentState.childState', {
  url: '/child',
  controller: 'ChildController',
  params: {
    parentParam: null
  }
});

$state.go('parentState', { param: 'value' });