Enhance shenyu-plugin-base module unit test

HI. I want to Enhance shenyu-plugin-base module unit test??make its coverage rate is more than 80% issue: https://github.com/dromara/shenyu/issues/1449#issue-890919183

??????Optimize shenyu-plugin-base module unit test

issue: https://github.com/dromara/shenyu/issues/1449#issue-890919183 ---- ??: "boush

Optimize shenyu-plugin-base module unit test

Task Task List: Optimize shenyu-plugin-base module unit test??make its coverage rate is more than 80%