code: public ServletHolder mapPathToServlet(String pathSpec,
                                            String servletName)
      {
          ServletHolder holder =(ServletHolder)_nameMap.get(servletName);
  
          if (!pathSpec.startsWith("/") && !pathSpec.startsWith("*"))
          {
              log.warn("pathSpec should start with '/' or '*' : "+pathSpec);
              pathSpec="/"+pathSpec;
          }
          
          if (holder==null)
              throw new IllegalArgumentException("Unknown servlet: "+servletName);
          _servletMap.put(pathSpec,holder);
          return holder;
      }
docs: Map a servlet to a pathSpec
  @param pathSpec The pathspec to map
  @param servletName The name of the servlet, which must have already been added.
  @return The servlet holder of the mapped servlet.