code: private Table resolve(boolean createIfNotExist) {
          HttpSession session = Stapler.getCurrentRequest().getSession(createIfNotExist);
          if (session==null) return null;
  
          Table t = (Table) session.getAttribute(Table.class.getName());
          if (t==null) {
              if (createIfNotExist)
                  session.setAttribute(Table.class.getName(), t=new Table());
              else
                  return null;
          }
          return t;
      }
docs: Obtains a {@link Table} associated with this session.