kotlin-spring-proxy-compatibility

@Transactional fails in Kotlin Spring applications when proxy interception breaks due to final-by-default class semantics or missing kotlin("plugin.spring") compiler plugin. Spring AOP proxying requires open classes and non-final methods to generate interceptable proxies for transactional, cacheable, and async annotations.

Diagnose Spring AOP proxy issues in Kotlin by analyzing proxy types, bean boundaries, and compiler plugin configuration. Check whether the proxy should exist, verify the call crosses the proxy boundary, and confirm kotlin("plugin.spring") and kotlin("plugin.jpa") plugins are enabled to restore interception.

Yes, the kotlin("plugin.spring") compiler plugin is required for @Cacheable and @Async annotations in Kotlin. It opens classes and methods that are final by default in Kotlin, allowing Spring to create the CGLIB proxies necessary for AOP interception to execute as expected.

Spring proxy interception fails with self-invocation in Kotlin because internal method calls bypass the proxy boundary and call the target directly. When a method annotated with @Transactional or @Retryable calls another annotated method within the same class, the interceptor does not execute.

Spring method security and retry annotations cannot intercept Kotlin final classes without the kotlin("plugin.spring") compiler plugin. Kotlin's final-by-default semantics prevent Spring from subclassing the target to generate proxies, breaking configuration proxies and method security interception.

Fix inconsistent @Cacheable behavior in a Kotlin Spring service by verifying the correct proxy strategy and confirming kotlin("plugin.spring") is applied. Ensure the cache call crosses the proxy boundary and check Open configuration to validate that interceptors execute as expected across runtime contexts.