通过构造对应单元测试用例辅助阅读Spring源码，加深对Spring源码的理解，并记录过程中遇到的知识点。
场景 构造两个类循环依赖的场景，验证：
- 通过字段方式注入，正常
- 通过构造函数注入，异常
测试用例 org.example.container.ioc.ContainerIocTestTest.testInjectByConstructorAutowired
通过构造函数注入报错信息如下：
WARNING: Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'beanC': Unsatisfied dependency expressed through constructor parameter 0: Error creating bean with name 'beanD': Unsatisfied dependency expressed through field 'beanC': Error creating bean with name 'beanC': Requested bean is currently in creation: Is there an unresolvable circular reference?