Jakarta Bean Validation - Bean Validation 2.0 CR 2 released

I’m very happy to announce the CR 2 release of the Bean Validation 2.0 spec!

The CR 2 is an update to the Proposed Final Draft (CR 1), addressing remarks and comments from reviewing all the changes. The updated spec document can be found here. To see the changes applied since the CR 1, check out this colored diff. If you’d like to see all the changes since Bean Validation 1.1, take a look at this diff. The updated API is available on Maven Central, using the GAV coordinates are javax.validation:validation-api:2.0.0.CR2.

What’s new since CR 1?

Given we are in the CR phase, most of the changes of this release naturally fall into the category of bug fixes, wording clarifications, formatting and other similar improvements. Reviewing the work done so far, and also working on the reference implementation and the TCK, we’ve decided to include two improvements to the API, too:

ConstraintDescriptor#validateUnwrappedValue() got renamed into getValueUnwrapping() (BVAL-674). The original method name sounded like a "command", whereas the new name makes clear it’s a "query" kind of method; also the members of the returned enum have been adapted to be in sync with the corresponding Unwrapping payload type names. We’ve also added a method ConstraintDescriptor#unwrap(Class), which will let providers expose additional functionality via extension interfaces, e.g. to explore new features which then can be standardized in a future spec revision.
@ConvertGroup#from() has a default value of Default.class now (BVAL-689). This simplifies group conversions in the common case where the default group is converted into another group.

Another interesting change is BVAL-613: when using the reference API JAR with the Java 9 module system, it will have the module name "java.validation" (following the recommendation in the spec appendix). This is done using the Automatic-Module-Name manifest header defined by Java 9.

Other changes include JavaDoc improvements and more clearly separating API types from examples in the spec. The complete list of all issues resolved for the CR 2 release can be found in the BVAL JIRA project. Corresponding releases of our reference implementation Hibernate Validator 6 and the TCK are also done today.

What’s new in Bean Validation 2.0?

The focus of Bean Validation 2.0 is supporting and taking advantage of Java SE 8.

For instance type annotations are used to validate the elements of generic containers: List<@NotNull @Email String> emails. There are new built-in constraints (@NotBlank, @NotEmpty, @Email, @FutureOrPresent, @PastOrPresent, @Positive, @PositiveOrZero, @Negative and @NegativeOrZero) and all built-in constraints are repeatable annotations now. Bean Validation 2.0 also supports the new Java 8 date and time types (JSR 310), the property types defined by JavaFX (StringProperty etc.) as well as java.util.Optional.

To learn more about all the new features in Bean Validation 2.0, check out this presentation which I recently gave at the jdk.io conference.

What can you do to help?

We’ll hand over the specification to the JCP for the Final Approval Ballot early next week. For the FAB release, we don’t expect any significant changes over today’s CR 2. If you’d like to help, reviewing the specification changes would be the best thing to do at this point. Also it’d be of great help if you tried out the reference implementation in your applications and let us know how it works. Any feedback is welcomed!

To post your feedback, just add a comment below, send a message to our mailing list or post in the Bean Validation forum. If you find a bug or have a specific feature request, please raise it in the issue tracker.

Everything in Bean Validation is open source, so you also can send in actual patches: be it to the API, the spec document, the TCK or the reference implementation. If you are interested, you can find out all the details to get started in the contribution guide.