docs: public final AbstractItem next(boolean allowUnavailable) throws SevereMessageStoreException
      {
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) SibTr.entry(this, tc, "next", Boolean.valueOf(allowUnavailable));
  
          AbstractItem found = null;
  
          // check from current position
          AbstractItemLink lookAt = (AbstractItemLink)advance();
          while (null != lookAt && null == found)
          {
              found = lookAt.matches(_filter, allowUnavailable);
              if (null == found)
              {
                  lookAt = (AbstractItemLink)advance();
              }
          }
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) SibTr.exit(this, tc, "next", found);
          return found;
      }