code: public File getWorkareaFile(String relativeServerWorkareaPath) {
          if (relativeServerWorkareaPath == null)
              return workarea;
          else
              return new File(workarea, relativeServerWorkareaPath);
      }
docs: Allocate a file in the server directory, e.g.
  usr/servers/serverName/workarea/relativeServerWorkareaPath
  
  @param relativeServerWorkareaPath
  relative path of file to create in the server's workarea
  @return File object for relative path, or for the server workarea itself if
  the relative path argument is null