Upgrade: spring boot to 3.x latest

[c5ms]

Why

Due to #141 , It's necessary to update the project with the latest spring boot version.
The DDD simple should have the modern technical stack to show how ddd gets implemented.
So, the project can be welcome to new committer with more ideas and best practices.

What

• Upgrade the spring boot to 3.0
• add spring doc with latest version for generating the open-api doc and embedded swagger-UI
• add micrometer support for web request and database accessing

[orende]

Why was this class renamed? Was it to avoid a namespace collision with JPA?

[c5ms]

yes, IMHO, this class should not use a single word.

[orende]

Can this dependency be injected into the constructor instead?

[c5ms]

I think it's hard and dangerous to do it since the injection currently has some circular.
It's the next step I'm planning.

[orende]

Okay, got it. In that case, could you add a comment to this field explaining that it cannot be moved into the constructor params due to the circular dependency problem? Otherwise, my knee-jerk reaction seeing that autowired field would be to inline it 😃

[c5ms]

I got the reason by new investigation and make it inline with constructor

[c5ms]

May I know why some beans are defined in the context file (like DDDSampleApplicationContext) but some are defined by the annotation?

I think the domain layer should not have the runtime knowledge like CDI, but the infrastructure and interfaces may can do it.

I have some idea for optimizing the bean definitions to:

1. no circular reference
2. no duplicate bean definition

But I'm wondering about how to define the beans with the original principle.

[orende]

Looking at the code, I can't find any beans that are defined outside the context files. Can you give an example of a bean you found that is declared outside of a context file?

[c5ms]

see HandlingReportServiceImpl this class is defined outside the context files.
and TrackCommandValidator this class is defined inside the context file but CargoTrackingController is using it by new .

[orende]

Right, CargoTrackingController should inject TrackCommandValidator instead of instantiating by new.

As for HandlingReportServiceImpl, using the @RestController annotation leads to significantly less configuration code, so I wouldn't want to refactor that to be instantiated programmatically in the context class.

[c5ms]

The bad news is that spring boot has released 3.4.0
https://github.com/spring-projects/spring-boot/releases/tag/v3.4.0
😑

[orende]

@c5ms We (the core maintainers) have reviewed the change now and have a couple of proposals:

1. We don't want to use Lombok in this project, so please revert those parts of the PR.
2. We'd like to have springdoc-openapi-starter-webmvc-ui moved out into a separate PR, so that we can review it separately.
3. We'd also like to have the micrometer dependency and changes moved out into a separate PR.

Once that is done, we feel the PR is ready for merge.

[c5ms]

@orende
I have reverted the using of lombok, you are right, we should demonstrate how to DDD with pure java.(if I got the correctly understanding of the comments)

[orende]

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