def build_exception_with_cause
  begin
    1 / 0
  rescue ZeroDivisionError
    1 / 0
  end
rescue ZeroDivisionError => exception
  return exception
end

exc = build_exception_with_cause
exc.cause # MRI: #<ZeroDivisionError: divided by 0>

exc = build_exception_with_cause
exc.cause # JRuby: nil