code: @Override
      public String getFilterName() {
          FilterConfig sc = getFilterConfig();
          if (sc == null) {
              throw new IllegalStateException(
                  lStrings.getString("err.servlet_config_not_initialized"));
          }
  
          return sc.getFilterName();
      }
docs: <p>Returns the name of this filter instance.
  See {@link FilterConfig#getFilterName}.</p>
  
  @return          the name of this filter instance
  
  @since Servlet 4.0