Inappropriate nested cascade validation of associations

This is complicated to reproduce as it requires several layers of associations, but it can be done at least if you have a single domain A with a one to many association to B which has another one to many on itself B, then another one to many from A to C which has a one to many to D which has one to many to E which then fails validation.

When A.validate() is called it results in the generated `fixedField` in `org.springframework.validation.AbstractBindingResult` is
`B[0].childB[0].A.C[0].D[0].E[4].value`.

The `validatedObjects` Set at this point contains A, B[0] and childB[0] has just been added.

This has occured I believe due to lines 245 of `grails.gorm.validation.PersistentEntityValidator` where it calls

```
if (associatedPersistentProperty instanceof Association) {
if(association.doesCascade(CascadeType.PERSIST, CascadeType.MERGE)) {
if(association.isBidirectional() && associatedPersistentProperty == association.inverseSide) {
// If this property is the inverse side of the currently processed association then
// we don't want to process it because that would cause a potential infinite loop
continue
}

cascadeToAssociativeProperty(
associatedObject,
errors,
associatedReflector,
(Association)associatedPersistentProperty,
validatedObjects)
}
}
```

I believe its actually supposed to check the cascade and bidirectionality of the associatedPersistentProperty rather than the original association which means the code should read

```
if (associatedPersistentProperty instanceof Association) {
if(((Association)associatedPersistentProperty).doesCascade(CascadeType.PERSIST, CascadeType.MERGE)) {
if(((Association)associatedPersistentProperty).isBidirectional() && associatedPersistentProperty == association.inverseSide) {
// If this property is the inverse side of the currently processed association then
// we don't want to process it because that would cause a potential infinite loop
continue
}

cascadeToAssociativeProperty(
associatedObject,
errors,
associatedReflector,
(Association)associatedPersistentProperty,
validatedObjects)
}
}
```

Alternatively, if the intent is to check the `association` rather than the `associatedPersistentProperty` the solution would be to check the `validatedObjects` set at line 112 and 113 to see if the associatedObject has already been validated.

```
if(associatedObject != null && proxyHandler?.isInitialized(associatedObject) && !validatedObjects.contains(associatedObject)) {
if(association.isOwningSide() || association.doesCascade(CascadeType.PERSIST, CascadeType.MERGE)) {
```

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issue.

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### Task List

- [x] Steps to reproduce provided
- [x] Stacktrace (if present) provided
- [ ] Example that reproduces the problem uploaded to Github
- [x] Full description of the issue provided (see below)

### Steps to Reproduce

See Above

### Expected Behaviour

Should not revalidated the associated property

### Actual Behaviour

Validated into the nested associated property.

### Environment Information

- **Operating System**: Mac OS Sierra
- **GORM Version:** 6.1.8
- **Grails Version (if using Grails):** 3.3.1
- **JDK Version:** 8u141-oracle

### Example Application

- TODO: link to github repository with example that reproduces the issue

Start in grails.gorm.validation.PersistentEntityValidator, especially the cascade logic around lines 245 and 112-113. Reproduce the nested A/B/C/D/E association case described in the issue, then determine whether cascade and inverse-side checks use the associated property correctly. Done means A.validate() no longer revalidates the inappropriate nested association.

Written by the indexing model from the issue text.