tomcat部署activiti-explorer.war包报错org.activiti.bpmn.exceptions.XMLException: src-resolve: 无法将名称 ‘exten

在Tomcat部署activiti-explorer.war报错，访问不了页面

报错信息

org.activiti.bpmn.exceptions.XMLException: src-resolve: 无法将名称 ‘extension’ 解析为 ‘element declaration’ 组件。

org.activiti.bpmn.exceptions.XMLException: src-resolve: 无法将名称 ‘extension’ 解析为 ‘element declaration’ 组件。
at org.activiti.bpmn.converter.BpmnXMLConverter.convertToBpmnModel(BpmnXMLConverter.java:280)
at org.activiti.engine.impl.bpmn.parser.BpmnParse.execute(BpmnParse.java:187)
at org.activiti.engine.impl.bpmn.deployer.BpmnDeployer.deploy(BpmnDeployer.java:136)
at org.activiti.engine.impl.persistence.deploy.DeploymentManager.deploy(DeploymentManager.java:58)
at org.activiti.engine.impl.cmd.DeployCmd.execute(DeployCmd.java:106)
at org.activiti.engine.impl.cmd.DeployCmd.execute(DeployCmd.java:37)
at org.activiti.engine.impl.interceptor.CommandInvoker.execute(CommandInvoker.java:24)
at org.activiti.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:57)
at org.activiti.spring.SpringTransactionInterceptor 1. d o I n T r a n s a c t i o n ( S p r i n g T r a n s a c t i o n I n t e r c e p t o r . j a v a : 47 ) a t o r g . s p r i n g f r a m e w o r k . t r a n s a c t i o n . s u p p o r t . T r a n s a c t i o n T e m p l a t e . e x e c u t e ( T r a n s a c t i o n T e m p l a t e . j a v a : 133 ) a t o r g . a c t i v i t i . s p r i n g . S p r i n g T r a n s a c t i o n I n t e r c e p t o r . e x e c u t e ( S p r i n g T r a n s a c t i o n I n t e r c e p t o r . j a v a : 45 ) a t o r g . a c t i v i t i . e n g i n e . i m p l . i n t e r c e p t o r . L o g I n t e r c e p t o r . e x e c u t e ( L o g I n t e r c e p t o r . j a v a : 31 ) a t o r g . a c t i v i t i . e n g i n e . i m p l . c f g . C o m m a n d E x e c u t o r I m p l . e x e c u t e ( C o m m a n d E x e c u t o r I m p l . j a v a : 40 ) a t o r g . a c t i v i t i . e n g i n e . i m p l . c f g . C o m m a n d E x e c u t o r I m p l . e x e c u t e ( C o m m a n d E x e c u t o r I m p l . j a v a : 35 ) a t o r g . a c t i v i t i . e n