同事问我，JSF项目发布的时候，为什么编译后的类放在classes发布是没问题的，而打包成jar放到lib下就包null错误呢？

很是纠结了一阵后，我找到了答案：

https://javaserverfaces.dev.java.net/issues/show_bug.cgi?id=1693

Managed beans declared only via javax.faces.bean annotations, and packaged only in a jar file in WEB-
INF/lib are not discovered by the application.

MBean 使用注解方式声明 而不是声明在faces-config.xml 打包放在WEB-INF/lib里
MBean无法被应用正确发现。

The real problem here was user error.  My testcase.zip did not have a faces-config.xml in the META-INF in the jar.  When I added one, it worked.  However, the spec says an empty or zero-length one should be sufficient also.  This assertion failed.  The attached changebundle fixes the problem of a zero-length or empty faces-config.xml file in a META-INF in a jar in WEB-INF/lib causing the app to fail to deploy.

大概意思是：
jar包中，在META-INF里需要一个空的faces-config.xml文件