docs: @Override
      public String getInUseSessionID(ServletRequest req, SessionAffinityContext sac) {
          String id = null;
          if (sac.isRequestedSessionIDFromSSL() && req != null) {
              id = getActualSSLSessionId(req);
          } else {
              // We may have been dispatched and a previous app created a session.
              // If so, the Id will be in the response id, and we need to use it
              id = sac.getResponseSessionID();
              if (id == null) {
                  id = sac.getRequestedSessionID();
              }
          }
          return id;
      }