Unable to update embedded class field

### 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

1. Create a simple grails 4.0.1, gorm 7.0.2.RELEASE (with mongo plugin support) application
2. Create one class in the groovy/src folder
```
//import grails.gorm.dirty.checking.DirtyCheck

//@DirtyCheck
class EmbeddedClass {
String aField
}
```
3. Create a domain class in grails-app
```
class DomainClass implements Serializable {

EmbeddedClass embeddedClass

static embedded = ['embeddedClass']

static constraints = {
}
}
```
4. Insert an entity
```
DomainClass.withNewTransaction {
def domain = new DomainClass()
domain.embeddedClass = new EmbeddedClass()
domain.embeddedClass.aField = "ogValue"
domain.save(flush: true, failOnError: true)
}
```
5. Try to update domain.embeddedClass.aField
```
@Secured(['IS_AUTHENTICATED_ANONYMOUSLY'])
def updateEmbedded() {
def domainClass = DomainClass.findById(1)
domainClass.embeddedClass = new EmbeddedClass()
domainClass.embeddedClass.aField = "anothervalue"
domainClass.save(flush:true, failOnError: true)

return respond("response": "response")
}
```
6. Check the value in the db.

### Expected Behaviour

Ability to update embedded class field.

### Actual Behaviour

Unable to update embedded class field. Tried with new entity (provided example), update only the field, tried to add (DirtyCheck annotation) as I saw in some other issue -> that will throw an exception. Relevant stacktrace is as follows:
```
java.lang.IllegalStateException: Either class [org.avora.lib.models.EmbeddedClass] is not a domain class or GORM has not been initialized correctly or has already been shutdown. Ensure GORM is loaded and configured correctly before calling any methods on a GORM entity.
at org.grails.datastore.gorm.GormEnhancer.stateException(GormEnhancer.groovy:467)
at org.grails.datastore.gorm.GormEnhancer.findStaticApi(GormEnhancer.groovy:298)
at org.grails.datastore.gorm.GormEnhancer.findStaticApi(GormEnhancer.groovy:294)
at org.grails.datastore.mapping.mongo.engine.codecs.PersistentEntityCodec.encodeUpdate(PersistentEntityCodec.groovy:285)
at org.grails.datastore.mapping.mongo.engine.codecs.PersistentEntityCodec.encodeUpdate(PersistentEntityCodec.groovy:203)
at org.grails.datastore.mapping.mongo.engine.codecs.PersistentEntityCodec.encodeEmbeddedUpdate(PersistentEntityCodec.groovy:443)
at org.grails.datastore.mapping.mongo.engine.codecs.PersistentEntityCodec.encodeUpdate(PersistentEntityCodec.groovy:251)
at org.grails.datastore.mapping.mongo.engine.codecs.PersistentEntityCodec.encodeUpdate(PersistentEntityCodec.groovy)
at org.grails.datastore.mapping.mongo.MongoCodecSession.flush(MongoCodecSession.groovy:158)
at org.grails.datastore.mapping.mongo.AbstractMongoSession.flush(AbstractMongoSession.java:74)
at org.grails.datastore.gorm.GormInstanceApi.doSave(GormInstanceApi.groovy:368)
at org.grails.datastore.gorm.GormInstanceApi.doSave(GormInstanceApi.groovy)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:101)
at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:323)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1217)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1041)
at org.codehaus.groovy.runtime.InvokerHelper.invokePogoMethod(InvokerHelper.java:1011)
at org.codehaus.groovy.runtime.InvokerHelper.invokeMethod(InvokerHelper.java:994)
at org.codehaus.groovy.runtime.InvokerHelper.invokeMethodSafe(InvokerHelper.java:97)
at org.grails.datastore.gorm.GormInstanceApi$_save_closure5.doCall(GormInstanceApi.groovy:180)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:101)
at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:323)
at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:263)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1041)
at groovy.lang.Closure.call(Closure.java:405)
at org.codehaus.groovy.runtime.ConvertedClosure.invokeCustom(ConvertedClosure.java:50)
at org.codehaus.groovy.runtime.ConversionHandler.invoke(ConversionHandler.java:122)
at com.sun.proxy.$Proxy112.doInSession(Unknown Source)
at org.grails.datastore.mapping.core.DatastoreUtils.execute(DatastoreUtils.java:319)
at org.grails.datastore.gorm.AbstractDatastoreApi.execute(AbstractDatastoreApi.groovy:40)
at org.grails.datastore.gorm.GormInstanceApi.save(GormInstanceApi.groovy:179)
at org.grails.datastore.gorm.GormEntity$Trait$Helper.save(GormEntity.groovy:153)
at org.grails.datastore.gorm.GormEntity$Trait$Helper$save$4.call(Unknown Source)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:47)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:115)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:135)
at org.mypackage.DomainClass.save(DomainClass.groovy)
at org.mypackage.DomainClass.save(DomainClass.groovy)
at org.grails.datastore.gorm.GormEntity$save.call(Unknown Source)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:47)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:115)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:127)
```

### Environment Information

- **Operating System**: macOS Catalina 10.15.4
- **GORM Version:** 7.0.2.RELEASE
- **Grails Version (if using Grails):** 4.0.1
- **JDK Version:** 1.8.0_231

### Example Application

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