* producerPrivKey load from vault

* add secret nil judge

* review changes

* add comment

* review change,  add unit test

* add comment

* add http close

* fix code smell

* test ci

* test ci

* upgeade vault version

* fix unit test, drop vault depends

* add more unit test

* fix code smell

* fix code review

* add privatekey method

* add private key method, change unit test

* use gomock

* use hashiCorpVault string in case