How to understand the spring reference documentation regarding @Autowired

Question

Hopefully this question is simple enough. I'm reading the Spring Framework Reference:beans-java section and I came across this usage example

The part that confuses me is the note at the end, specifically where it says

Note also that there is no need to specify @Autowired if the target bean defines only one constructor; in the example above, @Autowired is not necessary on the RepositoryConfig constructor.

I don't quite understand why I can remove @Autowired from RepositoryConfig()? What is the target bean in this case and what constructor are they referring to?

I attempted to reproduce this but the documentation doesn't provide the AccountRepository class or the TransferService class and I'm a noob so not sure what they should like look. So a reproducible example would be desirable.

Answer 1

Spring version before 4.3 required you to annotate the constructor you wanted to use with @Autowired. Even if your class had a single constructor.

As of Spring 4.3 when your class has a single constructor you can leave out the @Autowired on the constructor as Spring then automatically assumes you want to use that constructor.

See this blog for more information and here the Jira ticket.