code: public static DeleteException fromThrowable(Throwable cause) {
      return (cause instanceof DeleteException)
                     ? (DeleteException) cause
                     : new DeleteException(cause);
    }
docs: Converts a Throwable to a DeleteException. If the Throwable is a
  DeleteException, it will be passed through unmodified; otherwise, it will be wrapped
  in a new DeleteException.
  
  @param cause the Throwable to convert
  
  @return a DeleteException