code: public final Link getNextPhysicalLink() {
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) {
              SibTr.entry(this, tc, "getNextPhysicalLink", _positionString());
          }
          Link nextLink = _nextLink;
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) {
              SibTr.exit(this, tc, "getNextPhysicalLink", nextLink);
          }
          return nextLink;
      }
docs: This version returns the next physical link (which may be logically
  unlinked)
  
  @return the next link object or null if nothing left in the list to return