code: @NotNull
      public IntStream onClose(@NotNull final Runnable closeHandler) {
          Objects.requireNonNull(closeHandler);
          final Params newParams = Params.wrapWithCloseHandler(params, closeHandler);
          return new IntStream(newParams, iterator);
      }
docs: Adds close handler to the current stream.
  
  <p>This is an intermediate operation.
  
  @param closeHandler  an action to execute when the stream is closed
  @return the new stream with the close handler
  @since 1.1.8