struts2.1.8 客户端验证的问题
就是一个简单的客户端验证，但是编译都不能通过，
代码以及其他配置应该不会有问题，因为我把form的validate设置为false采用服务端验证一切正常，但是设为true就不行了。


下面是错误提示:
严重: 

Method public java.util.List org.apache.struts2.components.Form.getValidators(java.lang.String) threw an exception when invoked on org.apache.struts2.components.Form@a218a5
The problematic instruction:
----------
==> list tag.getValidators("${tagName}") as validator [on line 46, column 9 in template/xhtml/form-close-validate.ftl]
 in include "/${parameters.templateDir}/xhtml/form-close-validate.ftl" [on line 25, column 1 in template/xhtml/form-close.ftl]
----------

Java backtrace for programmers:
----------
freemarker.template.TemplateModelException: Method public java.util.List org.apache.struts2.components.Form.getValidators(java.lang.String) threw an exception when invoked on org.apache.struts2.components.Form@a218a5
at freemarker.ext.beans.SimpleMethodModel.exec(SimpleMethodModel.java:130)
at freemarker.core.MethodCall._getAsTemplateModel(MethodCall.java:93)
at freemarker.core.Expression.getAsTemplateModel(Expression.java:89)
at freemarker.core.IteratorBlock.accept(IteratorBlock.java:94)
at freemarker.core.Environment.visit(Environment.java:209)
at freemarker.core.IteratorBlock$Context.runLoop(IteratorBlock.java:167)
at freemarker.core.Environment.visit(Environment.java:416)
at freemarker.core.IteratorBlock.accept(IteratorBlock.java:102)
at freemarker.core.Environment.visit(Environment.java:209)
at freemarker.core.MixedContent.accept(MixedContent.java:92)
at freemarker.core.Environment.visit(Environment.java:209)
at freemarker.core.ConditionalBlock.accept(ConditionalBlock.java:79)
at freemarker.core.Environment.visit(Environment.java:209)
at freemarker.core.MixedContent.accept(MixedContent.java:92)
at freemarker.core.Environment.visit(Environment.java:209)
at freemarker.core.Environment.include(Environment.java:1482)
at freemarker.core.Include.accept(Include.java:169)
at freemarker.core.Environment.visit(Environment.java:209)
at freemarker.core.MixedContent.accept(MixedContent.java:92)
at freemarker.core.Environment.visit(Environment.java:209)
at freemarker.core.Environment.process(Environment.java:189)
at freemarker.template.Template.process(Template.java:237)
at org.apache.struts2.components.template.FreemarkerTemplateEngine.renderTemplate(FreemarkerTemplateEngine.java:182)
at org.apache.struts2.components.UIBean.mergeTemplate(UIBean.java:559)
at org.apache.struts2.components.UIBean.end(UIBean.java:513)
at org.apache.struts2.views.jsp.ComponentTagSupport.doEndTag(ComponentTagSupport.java:42)
at org.apache.jsp.register_jsp._jspx_meth_s_005fform_005f0(register_jsp.java:168)
at org.apache.jsp.register_jsp._jspService(register_jsp.java:80)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:377)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:88)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)