Support proxy-less @Configuration classes unchanged from a developer POV

[sdeleuze]

See spring-attic/spring-native#248 for more details. We could probably start by doing such transformation only on configuration classes without @Bean to handle the default @SpringBootApplication case. Step 2 could be to do this transformation only if there is no cross @Bean method invocation. cc @aclement

[dsyer]

Currently we don't modify user's code. I don't like doing that really. Don't you think it would be better to warn or fail?

[sdeleuze]

I understand your hesitation but at the same time supporting Spring Boot application unchanged from a programming model perspective is a mandatory goal of ours IMO.

About that @aclement has raised a very interesting point that could change the scope of that issue.

With build time transformation it is possible to behave in the right way out of the box by modifying configuration classes directly to include the necessary guards around multiple requests to a bean method without creating any proxies... I wrote some code to do this in here: https://github.com/aclement/spring-boot-nox/blob/master/src/main/java/io/spring/nox/optimizer/collectors/ConfigurationClassCollectorRewriter.java#L195 - always correct behaviour with no configuration proxies.

I am not sure what kind of modification will be needed, but I tend to think some kind of modification on configuration classes will be needed at least for those with cross @Bean method invocations.

[dsyer]

Latest snapshots now support proxyBeanMethods=true by generating subclass implementations at build time and using those in the initializer.