mvn package时，报错A required class is missing: com/thoughtworks/xstream/io/HierarchicalStreamDriver

今天在项目中打包时报错，提示如下：

　[ERROR] Failed to execute goal org.apache.maven.plugins:maven-war-plugin:2.1:war (default-war) on project hadoop-auth-examples: Execution default-war of goal org.apache.maven.plugins:maven-war-plugin:2.1:war failed: Unable to load the mojo 'war' in the plugin 'org.apache.maven.plugins:maven-war-plugin:2.1'. A required class is missing: com/thoughtworks/xstream/io/HierarchicalStreamDriver

1、先检查依赖是否添加；

2、查看下载下来的jar包是否完整（删除文件夹让maven重新下载）；