HorizontalSplitPanel

Hello all,

i am a newbie here.
I wanted to use HorizontalSplitPanel on my Vaadin Project.
But why was there an error on my liferay portal that said

Widgetset does not contain implementation for com.vaadin.ui.HorizontalSplitPanel. Check its @ClientWidget mapping, widgetsets GWT module description file and re-compile your widgetset. In case you have downloaded a vaadin add-on package, you might want to refer to add-on instructions.

i read this post https://vaadin.com/forum/-/message_boards/view_message/309452
but i dont really understand and know what to do.

Can anyone please explain me?

Thank you