install chaosblade-exec-service error

[zhenjia001]

Issue Description

Type: bug report or feature request

Describe what happened (or what feature you want)

Describe what you expected to happen

How to reproduce it (as minimally and precisely as possible)

Error MSG:
Exception in thread "main" java.lang.NullPointerException
at com.alibaba.chaosblade.exec.service.build.BuildUtil.createClassLoader(BuildUtil.java:83)
at com.alibaba.chaosblade.exec.service.build.BuildUtil.generatePluginSpec(BuildUtil.java:52)
at com.alibaba.chaosblade.exec.service.build.SpecMain.main(SpecMain.java:32)
[ERROR] Command execution failed.

BG:Missing directory plugins

Tell us your environment

Anything else we need to know?