feature #12005 [Validator] Added "payload" option to all constraints for attaching domain-specific data (webmozart)

This PR was merged into the 2.6-dev branch.

Discussion
----------

[Validator] Added "payload" option to all constraints for attaching domain-specific data

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #7273
| License       | MIT
| Doc PR        | TODO

The "payload" option can be used to pass whatever data should be attached to a constraint for an application:

```php
/**
 * Domain-specific error codes
 * @NotNull(payload="100")
 */

/**
 * Structured domain-specific data
 * @NotNull(payload={"display": "inline", "highlight": false})
 */
```

The term "payload" is borrowed from JSR-303.

Commits
-------

e8b7c6d [Validator] Added "payload" option to all constraints for attaching domain-specific data

src/Symfony/Component/Validator/CHANGELOG.md

@@ -13,6 +13,7 @@ CHANGELOG
  * deprecated `ClassMetadata::getMemberMetadatas()`
  * deprecated `ClassMetadata::addMemberMetadata()`
  * [BC BREAK] added `Mapping\MetadataInterface::getConstraints()`
+ * added generic "payload" option to all constraints for attaching domain-specific data
 
 2.5.0
 -----

src/Symfony/Component/Validator/Constraint.php

@@ -50,6 +50,12 @@ abstract class Constraint
      */
     const PROPERTY_CONSTRAINT = 'property';
 
+    /**
+     * Domain-specific data attached to a constraint
+     * @var mixed
+     */
+    public $payload;
+
     /**
      * Initializes the constraint with options.
      *