How to add submenu for plugin on left side

how to add submenu for plugin on left side?

Which version of Kibana? And can you provide some more details about what you are trying to do? I'm not sure what you're asking for when you ask about a submenu on the left side. Some screenshots or a sketch or something may help illustrate what you mean.

version kibana 5.0
as you know, one plugin can add one or more menu items on left side. but they are not nested. is there any way to add a nested menu for plugin? like below

menu1
menu2
-----menu2.1
-----menu2.2
menu3

any response about cascading menu?