我这里只是找到了问题的解决方法，具体原因并不知晓，如果有哪位大佬知道问题原因的话还请指点小弟一二，在这里先谢谢了！！
下面的方法如果直接用Themeleaf解析employee_update则不会出现这个问题，但是用转发去映射上面方法的路径，再通过Themeleaf解析去转发页面则会出现这个错误，我很纳闷，Themeleaf也是通过转发的方式，我用转发路径再使用Themeleaf解析去转发应该也差不多啊，为什么最后会出现异常呢？然后我根据log的提示，尝试在上面方法中加了一个Employee的对象参数，程序就正常了
根据我的理解，request域中的数据转发多次应该也不会丢失，实际上虽然出现了异常，但在页面上还是出现了在getEmployeeById方法封装的Employy对象的部分数据，只是有一部分不显示了，也不知道是什么原理，在toEmployeeUpdate方法中加了一个Employee的对象参数后，才没有出现数据丢失的情况。
报错信息：
Caused by: org.thymeleaf.exceptions.TemplateProcessingException: Error during execution of processor 'org.thymeleaf.spring5.processor.SpringInputRadioFieldTagProcessor' (template: "/employee_update" - line 14, col 56) at org.thymeleaf.processor.element.AbstractAttributeTagProcessor.doProcess(AbstractAttributeTagProcessor.java:117) at org.thymeleaf.processor.element.AbstractElementTagProcessor.process(AbstractElementTagProcessor.java:95) at org.thymeleaf.util.ProcessorConfigurationUtils$ElementTagProcessorWrapper.process(ProcessorConfigurationUtils.java:633) at org.thymeleaf.engine.ProcessorTemplateHandler.handleStandaloneElement(ProcessorTemplateHandler.java:918) at org.thymeleaf.engine.StandaloneElementTag.beHandled(StandaloneElementTag.java:228) at org.thymeleaf.engine.TemplateModel.process(TemplateModel.java:136) at org.thymeleaf.engine.TemplateManager.parseAndProcess(TemplateManager.java:661) at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1098) at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1072) at org.thymeleaf.spring5.view.ThymeleafView.renderFragment(ThymeleafView.java:366) at org.thymeleaf.spring5.view.ThymeleafView.render(ThymeleafView.java:190) at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1394) at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1139) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1078) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:961) at org.springframework.web.servlet.frameworkServlet.processRequest(frameworkServlet.java:1006) ... 54 common frames omitted Caused by: java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'employee' available as request attribute at org.springframework.web.servlet.support.BindStatus.(BindStatus.java:153) at org.springframework.web.servlet.support.RequestContext.getBindStatus(RequestContext.java:903) at org.thymeleaf.spring5.context.webmvc.SpringWebMvcThymeleafRequestContext.getBindStatus(SpringWebMvcThymeleafRequestContext.java:227) at org.thymeleaf.spring5.util.FieldUtils.getBindStatusFromParsedexpression(FieldUtils.java:306) at org.thymeleaf.spring5.util.FieldUtils.getBindStatus(FieldUtils.java:258) at org.thymeleaf.spring5.util.FieldUtils.getBindStatus(FieldUtils.java:227) at org.thymeleaf.spring5.processor.AbstractSpringFieldTagProcessor.doProcess(AbstractSpringFieldTagProcessor.java:174) at org.thymeleaf.processor.element.AbstractAttributeTagProcessor.doProcess(AbstractAttributeTagProcessor.java:74) ... 69 common frames omitted
