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# `spring-boot-starter-aop` was renamed, not removed

Every pre-Boot-4 AOP or Resilience4j guide tells you to add `spring-boot-starter-aop` when an
annotation (`@Retryable`, `@ConcurrencyLimit`, Resilience4j's `@CircuitBreaker`, plain `@Aspect`
beans, anything proxy-based) needs AspectJ on the classpath. On Boot 4.1, adding that dependency
breaks the build before the application ever starts:

```
[ERROR] 'dependencies.dependency.version' for org.springframework.boot:spring-boot-starter-aop:jar is missing.
```

Captured by [`scripts/reproduce-starter-aop-break.sh`](../scripts/reproduce-starter-aop-break.sh)
against the minimal [`broken-example/pom.xml`](../broken-example/pom.xml), which adds only that
one dependency: [`00a-starter-aop-build-error.txt`](output/00a-starter-aop-build-error.txt).

## It was renamed, not dropped

It is tempting to read that error as "the starter is gone, assemble `spring-aop` and
`aspectjweaver` by hand instead" -- an earlier version of the sibling post this repo also serves
said exactly that. It is half right and half wrong. Maven Central's `maven-metadata.xml` for both
artifact IDs, read together, settles it:
[`00b-starter-aspectj-metadata-timeline.txt`](output/00b-starter-aspectj-metadata-timeline.txt).

`spring-boot-starter-aop`'s last-ever published version is `4.0.0-M2`. `spring-boot-starter-aspectj`'s
first-ever published version is `4.0.0-M3` -- the very next milestone in the same 4.0 line, and it
carries straight through to the 4.0.0 GA and every 4.1.x release since. That is a rename at a
specific milestone boundary, not an unrelated new artifact and not a starter dropped with nothing
replacing it.

The renamed starter's own published POM confirms it bundles exactly the two jars this module's
`pom.xml` needs:
[`00c-starter-aspectj-pom-dependencies.txt`](output/00c-starter-aspectj-pom-dependencies.txt).

```xml
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-aspectj</artifactId>
</dependency>
```

is all this module adds (see [`pom.xml`](../pom.xml)) -- one line, version-managed by the parent
POM like any other starter, resolving to `spring-aop` + `aspectjweaver` underneath. Assembling
those two dependencies by hand still works and behaves identically, since it's what the starter
does anyway, but there's no longer a reason to: the starter has the same name shape as every
other Boot starter, it's just spelled `aspectj` instead of `aop` from the 4.0 line onward.

<blockquote>If you're on a build that still references <code>spring-boot-starter-aop</code> after
upgrading to Boot 4, the fix is a rename in your <code>pom.xml</code>, not a rewrite: swap the
<code>artifactId</code> to <code>spring-boot-starter-aspectj</code> and nothing else changes.</blockquote>

## Going deeper

- [`pom.xml`](../pom.xml) -- this module's own dependency, with the corrected comment
- Maven Central: [`spring-boot-starter-aop/maven-metadata.xml`](https://repo1.maven.org/maven2/org/springframework/boot/spring-boot-starter-aop/maven-metadata.xml) and [`spring-boot-starter-aspectj/maven-metadata.xml`](https://repo1.maven.org/maven2/org/springframework/boot/spring-boot-starter-aspectj/maven-metadata.xml) -- rel="nofollow"
- [Resilience4j Circuit Breaker in Spring Boot 4.1: What It's Still For](https://ankurm.com/resilience4j-circuit-breaker-spring-boot/) -- the sibling post this same correction applies to

← [What is left for Resilience4j](06-what-is-left-for-resilience4j.md) | [Migrating from spring-retry](07-migrating-from-spring-retry.md) →