Migrating Spring Boot Starters: From spring.factories to AutoConfiguration.imports

If you are a Spring Boot user, you know that adding a feature is as easy as adding the corresponding starter dependency in Maven or Gradle, without writing XML or Java configuration classes.

Behind the scenes, Spring Boot does not eliminate the beans you would normally configure; it provides default configuration classes and uses the /META-INF/spring.factories file to list them. When the application starts, Spring Boot reads this file from each starter and loads the specified configuration classes.

Starting with Spring Boot 2.7, the /META-INF/spring.factories file is deprecated and will be removed in Spring Boot 3. Custom starter developers must migrate to the new mechanism.

For example, a Swagger starter previously had the following /META-INF/spring.factories content:

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
  com.spring4all.swagger.SwaggerAutoConfiguration

To migrate, create a new file

/META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports

and place the fully‑qualified configuration class name inside:

com.spring4all.swagger.SwaggerAutoConfiguration

Note that the new file resides under an additional spring directory.