Improve and fix the Javadoc link

[christophejan]

With Spring Batch 6, Javadoc has moved. However, some current documentation still uses a Javadoc link pointing to version 5.2.4:
https://docs.spring.io/spring-batch/docs/current/api/

For example, in the following paragraphs:

• https://docs.spring.io/spring-batch/reference/job/advanced-meta-data.html#JobParametersIncrementer
• https://docs.spring.io/spring-batch/reference/testing.html#mockingDomainObjects

I believe it would be clearer if Spring Batch followed the same pattern as Spring Boot, which redirects https://docs.spring.io/spring-boot/docs/current/api/org/ to https://docs.spring.io/spring-boot/api/java/org/

[answndud]

Hi, I'd like to work on this issue. I'll update the reference docs to use the current Spring Batch 6 Javadoc URL pattern and open a PR.

[answndud]

Opened a PR for this: #5313. It updates the outdated Javadoc links in the reference docs to point to the Spring Batch 6 API path.