Double saved

I want to save an object, but first I need to get its `ID` to update another property of the same object. I am doing this:

```
if (instance.validate()) {
instance.save() // now I have an id
instance.code = String.format("%014d", instance.id)
instance.save()
}
```

The domain object is
```
class Product {

final static String DEFAULT_CODE = "XXXX-XXXX-XXXX"

String code = DEFAULT_CODE
String description

static constraints = {
code size: 14..14
}
}
```

But when I get the object from the data base, the `code` property doesn't have the new value. I created an integration test to show this:

```
void "test double saved"() {
given:
RestBuilder rest = new RestBuilder()

when: "save a new product"
RestResponse response = rest.post("http://localhost:${serverPort}/product") {
json([
description: "screw"
])
}

then: "the code will be different to default value"
response.status == 201
Product product = Product.getAll().first()
product
product.code != Product.DEFAULT_CODE

cleanup:
Product.withNewSession {
Product.withNewTransaction {
Product.getAll()*.delete()
}
}
}
```
The second call to save() is ignored.

Here is the sample app: https://github.com/AmaliaMV/neo4j-doubleSaved

The versions I am using are:

```
grailsVersion=3.3.5
gormVersion=6.1.10.BUILD-SNAPSHOT
grailsNeo4jPluginVersion=6.2.0.BUILD-SNAPSHOT
```

However, I checked that this is happening too if I use hibernate instead of neo4j.

Start with the sample app and the integration test shown in the issue, reproducing the POST to /product and inspecting Product.getAll().first(). Trace the two save calls in the Grails/GORM persistence path, then verify that the generated code is persisted when using both the reported Neo4j and Hibernate configurations.

Written by the indexing model from the issue text.