docs: public final Item findOldestItem() throws MessageStoreException
      {
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
              SibTr.entry(this, tc, "findOldestItem");
  
          ItemCollection ic = ((ItemCollection) _getMembership());
          if (null == ic)
          {
              if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
                  SibTr.exit(this, tc, "findOldestItem");
              throw new NotInMessageStore();
          }
          Item item = null;
          if (ic != null)
          {
              item = (Item) ic.findOldestItem();
          }
  
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
              SibTr.exit(this, tc, "findOldestItem", item);
          return item;
      }