code: public ServletHolder addServlet(String name,
                                      String pathSpec,
                                      String servletClass)
      {
          return addServlet(name,pathSpec,servletClass,null);
      }
docs: Add a servlet.
  @param name The servlet name.
  @param pathSpec A path specification to map this servlet to.
  @param servletClass The class name of the servlet.
  @return The ServletHolder for the servlet.