@groovy.transform.CompileStatic
class Sitemesh3ViewResolverDefinitionPostProcessor
extends SiteMeshViewResolverPostProcessor

Grails-flavoured SiteMeshViewResolverPostProcessor — the upstream bean-definition wrap mode (sitemesh.viewResolver.wrapMode=bean-definition) expressed with Grails semantics. It rewrites the jspViewResolver bean definition into a GrailsSiteMeshViewResolver definition, so that every instantiation of the bean — however early — yields the decorating resolver.

Wrapping at the bean-definition level (rather than post-processing the bean instance) closes an initialization-order race: jspViewResolver is registered lazy, so it is instantiated by whichever component first asks for it. If that consumer is initialized before the SiteMesh BeanPostProcessor takes effect — Spring Boot's ContentNegotiatingViewResolver collecting every ViewResolver while it initializes is one such consumer — it captures the raw, undecorating resolver and keeps rendering through it, silently disabling layouts. The rewrite itself — embedding the original definition as an anonymous inner bean, invisible to type scans — is inherited from the upstream implementation; this subclass adds only the Grails-specific guards.

Runs after GroovyPagesPostProcessor (which contributes the default GSP resolver definition when no plugin has registered one) so the definition being wrapped is final, whether it came from grails-gsp, the scaffolding plugin, or the application.