scenerio: Runtime Error:
```
java.lang.SecurityException: class "javax.servlet.FilterRegistration"‘s signer information does not match signer information of other classes in the same package
```
google, and know this is a confliction of Java.servlet
Solution:
Using idea, view -> Tool view —> maven projects
Select your module, and show dependencies
Ctrl-f on your dependency graph, and search your conflict lib, and exclude it.