在多模块项目中使用Maven shade插件 - NullPointerException

I have a scenario where-in I need to create an uber jar of a multi module maven project including all modules and their dependencies. I tried using maven shade plugin. but it seems to work only when I use it at the module level. If I add the plugin entry in parent pom then the build breaks (it tries to shade the parent pom)I have a scenario where-in I need to create an