准备
- stapler：Stapler is a library that “staples” your application objects to URLs, making it easier to write web applications. The core idea of Stapler is to automatically assign URLs for your objects, creating an intuitive URL hierarchy.
- AST：抽象语法树(Abstract Syntax Tree)
入口
jenkins.model.Jenkins class是整个web应用程序的入口，查看此类源码，可以看到在类上标记了@ExportedBean注解。
#pipeline-model-definition-plugin
[pipeline-model-definition-plugin(https://github.com/jenkinsci/pipeline-model-definition-plugin/wiki/getting-started)
声明式 pipeline 模型定义插件；
