code: function ListCollectionIdsResponse(properties) {
                      this.collectionIds = [];
                      if (properties)
                          for (var keys = Object.keys(properties), i = 0; i < keys.length; ++i)
                              if (properties[keys[i]] != null)
                                  this[keys[i]] = properties[keys[i]];
                  }
docs: Properties of a ListCollectionIdsResponse.
  @memberof google.firestore.v1
  @interface IListCollectionIdsResponse
  @property {Array.<string>|null} [collectionIds] ListCollectionIdsResponse collectionIds
  @property {string|null} [nextPageToken] ListCollectionIdsResponse nextPageToken
   
  Constructs a new ListCollectionIdsResponse.
  @memberof google.firestore.v1
  @classdesc Represents a ListCollectionIdsResponse.
  @implements IListCollectionIdsResponse
  @constructor
  @param {google.firestore.v1.IListCollectionIdsResponse=} [properties] Properties to set