docs: @Override
      public void execute() throws MojoExecutionException {
          
          if (StringUtils.isEmpty(moduleSource) && ignoreMissingSource) {
              getLog().info("No help module source specified.");
              return;
          }
          
          init("help", moduleBase);
          registerLoader(new SourceLoader("javahelp", "*.hs", ZipIterator.class));
          registerLoader(new SourceLoader("ohj", "*.hs", ZipIterator.class));
          registerLoader(new ChmSourceLoader());
          registerExternalLoaders();
          SourceLoader loader = sourceLoaders.get(moduleFormat);
          
          if (loader == null) {
              throw new MojoExecutionException("No source loader found for format " + moduleFormat);
          }
          
          try {
              String sourceFilename = FileUtils.normalize(baseDirectory + "/" + moduleSource);
              HelpProcessor processor = new HelpProcessor(this, sourceFilename, loader);
              processor.transform();
              addConfigEntry("help", moduleId, processor.getHelpSetFile(), moduleName, getModuleVersion(), moduleFormat,
                  moduleLocale);
              assembleArchive();
          } catch (Exception e) {
              throw new MojoExecutionException("Unexpected error.", e);
          }
      }