code: private String getViewContent(final Map<String, Object> dataModel) {
          if (null == configuration) {
              initTemplateEngineCfg();
          }
  
          try {
              final Template template = configuration.getTemplate("plugin.ftl");
              final StringWriter sw = new StringWriter();
  
              template.process(dataModel, sw);
  
              return sw.toString();
          } catch (final Exception e) {
              // This plugin has no view
  
              return "";
          }
      }
docs: Gets view content of a plugin. The content is processed with the
  specified data model by template engine.
  
  @param dataModel the specified data model
  @return plugin view content