message: Method should be optional for back-compat
diff: @@ -153,7 +153,7 @@ export interface IDb {
  * Removes a collection or view from the database.
  * The method also removes any indexes associated with the dropped collection.
  */
  - dropCollection(name: string): Promise<boolean>;
  + dropCollection?(name: string): Promise<boolean>;
  }
  export interface IDbFactory {
  