Object management in multi-user environment(JAVA)?

Question

Java

Comrades, I ask for help.
I'm writing a project on Vaadin (but I think it's not important)
Tell me what approaches are used to implement this task.
There is an object "Table"
Each user generates a table for himself by creating a new object, that is, each time something like new Grid () is called.
But I would like to create only one object for a specific user within the user session. As far as I understand singlton will not work, because it will create one table object for all users.
It only comes to mind to create a certain SET collection, somehow bind it to a specific user session. And work only through it.
In general, could you enlighten how it is usually done