maven conflict solution:

1. 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
   ```
2. google, and know this is a confliction of Java.servlet
3. Solution:
   1. Using idea, view -> Tool view —> maven projects
   2. Select your module, and show dependencies
   3. Ctrl-f on your dependency graph, and search your conflict lib, and exclude it.
4. fixed.

<Maven><Dependency><Conflict>