code: public Folder createFolder(long parentFolderId, Folder folder) throws SmartsheetException {
  
          return this.createResource("folders/" + parentFolderId + "/folders", Folder.class, folder);
      }
docs: Create a folder.
  
  It mirrors to the following Smartsheet REST API method: POST /folder/{id}/folders
  
  Exceptions:
  IllegalArgumentException : if folder is null
  InvalidRequestException : if there is any problem with the REST API request
  AuthorizationException : if there is any problem with the REST API authorization(access token)
  ServiceUnavailableException : if the REST API service is not available (possibly due to rate limiting)
  SmartsheetRestException : if there is any other REST API related error occurred during the operation
  SmartsheetException : if there is any other error occurred during the operation
  
  @param parentFolderId the parent folder id
  @param folder the folder to create
  @return the folder
  @throws SmartsheetException the smartsheet exception