# 1. The jakarta.validation namespace, and what Bean Validation 3.1 actually changed

[README](../README.md) | Next: [Record validation](02-record-validation.md)

Source: [`ContactForm.java`](../src/main/java/com/ankurm/customvalidation/dto/ContactForm.java),
[`SpamMessageCheck.java`](../src/main/java/com/ankurm/customvalidation/validator/SpamMessageCheck.java).
Transcripts: [`docs/output/00-jakarta-validation-api-manifest.txt`](output/00-jakarta-validation-api-manifest.txt),
[`docs/output/00b-hibernate-validator-manifest.txt`](output/00b-hibernate-validator-manifest.txt).

## The defect this module replaces

The original version of the companion article this module backs used
`javax.validation.constraints.NotBlank`, `javax.validation.Constraint`, and so on throughout --
the pre-Jakarta-EE-9 namespace. That package was already wrong for any Spring Boot 3+ application
by the time the article was first published: Spring Boot 3.0 moved its entire dependency tree from
`javax.*` to `jakarta.*` in December 2022, and `javax.validation.*` classes are simply not on the
classpath of a `spring-boot-starter-validation` 3.x or 4.x application. Every class in this module
uses `jakarta.validation.*` instead. If you have a codebase still on `javax.validation`, it did not
survive the Boot 2 to 3 upgrade and needs the same mechanical rename this module already reflects.

## What Spring Boot 4.1.1 actually pins, checked directly

Rather than trust a blog's version claim (including an older draft of this one), the fact was
checked the way this repository always checks it: build a throwaway project against
`spring-boot-starter-parent:4.1.1` and run `mvn dependency:tree`.

```
[INFO] +- org.springframework.boot:spring-boot-starter-validation:jar:4.1.1:compile
[INFO] |  \- org.springframework.boot:spring-boot-validation:jar:4.1.1:compile
[INFO] |     \- org.hibernate.validator:hibernate-validator:jar:9.1.3.Final:compile
[INFO] |        +- jakarta.validation:jakarta.validation-api:jar:3.1.1:compile
```

Then confirmed a second, independent way: open the actual jars this application loads at runtime
and read their own manifests, rather than trusting the dependency tree's coordinates alone.

```
$ mvn test   # ClasspathVersionTest
```

<pre><code class="language-none">Class: jakarta.validation.Validation
Jar file: jakarta.validation-api-3.1.1.jar
Bundle-SymbolicName: jakarta.validation.jakarta.validation-api
Bundle-Version: 3.1.1
Implementation-Version: null</code></pre>

([`docs/output/00-jakarta-validation-api-manifest.txt`](output/00-jakarta-validation-api-manifest.txt))

<pre><code class="language-none">Class: org.hibernate.validator.internal.engine.ValidatorFactoryImpl
Jar file: hibernate-validator-9.1.3.Final.jar
Implementation-Title: hibernate-validator
Implementation-Version: 9.1.3.Final</code></pre>

([`docs/output/00b-hibernate-validator-manifest.txt`](output/00b-hibernate-validator-manifest.txt))

Spring Boot 4.1.1 pins **Hibernate Validator 9.1.3.Final**, the reference implementation of
**Jakarta Validation 3.1** -- the spec revision released in 2024 as part of Jakarta EE 11.

## What is actually new in 3.1 (not a rename of 3.0)

Three real changes, not a version-number bump for its own sake:

- **The specification itself was renamed** from "Jakarta Bean Validation" to "Jakarta Validation."
  The namespace (`jakarta.validation.*`) and the annotations you already know
  (`@NotBlank`, `@Size`, `@Valid`, `@Constraint`) are unchanged -- this is a spec-title change, not
  an API break.
- **The minimum required Java version moved to 17.** Not a concern for anything already running
  JDK 21 or 25, but it is the reason Hibernate Validator 9.x cannot be backported to run on
  Java 11.
- **Record validation is now explicitly specified**, closing a real gap in 3.0 where the spec was
  silent on how a constraint on a record component should behave. That is substantial enough to
  earn its own chapter -- see below.

## Going deeper

- [Jakarta Validation news and release history](https://beanvalidation.org/news/) (rel="nofollow")
- [Hibernate Validator reference guide](https://docs.hibernate.org/stable/validator/reference/en-US/html_single/) (rel="nofollow")
- Next: [Record validation](02-record-validation.md)