code: private RebelXmlBuilder buildJar() throws MojoExecutionException {
      RebelXmlBuilder builder = createXmlBuilder();
      buildClasspath(builder);
  
      // if user has specified any web elements, then let's generate these in the result file.
      if (web != null && web.getResources() != null && web.getResources().length != 0) {
        generateDefaultWeb = false; // but don't generate default web element because this folder is most likely missing.
        buildWeb(builder);
      }
  
      return builder;
    }
docs: Build jar configuration.
  
  @return
  @throws MojoExecutionException