### Search before asking - [X] I had searched in the [issues](https://github.com/apache/eventmesh/issues?q=is%3Aissue) and found no similar issues. ### Question <img width="640" alt="image" src="https://user-images.githubusercontent.com/91315508/155280074-b8447ff3-d739-4cfa-a31d-02b3b9cd63cf.png"> <img width="640" alt="image" src="https://user-images.githubusercontent.com/91315508/155280209-122da610-c46f-4250-9243-4f3cd28b7816.png"> <img width="640" alt="image" src="https://user-images.githubusercontent.com/91315508/155280770-cef53fb6-ad8b-47cf-bc2d-ccbcf139c057.png"> AdminController, TopicsHandler, NetUtils, RequestMapping classes have reusable String constants. Suggestion: Create a constant class under the admin package for these constants.
