code: public CmsFlexRequestDispatcher getRequestDispatcherToExternal(String vfs_target, String ext_target) {
  
          return new CmsFlexRequestDispatcher(
              m_controller.getTopRequest().getRequestDispatcher(ext_target),
              CmsLinkManager.getAbsoluteUri(vfs_target, m_controller.getCmsObject().getRequestContext().getUri()),
              ext_target);
      }
docs: Replacement for the standard servlet API getRequestDispatcher() method.<p>
  
  This variation is used if an external file (probably JSP) is dispatched to.
  This external file must have a "mirror" version, i.e. a file in the OpenCms VFS
  that represents the external file.<p>
  
  @param vfs_target the OpenCms file that is a "mirror" version of the external file
  @param ext_target the external file (outside the OpenCms VFS)
  
  @return the constructed CmsFlexRequestDispatcher