Grails how to prevent save class with empty values - http

Question

I have a parent class that have a children class with no required fields. The save form has the inputs for the parent and children class.
The problem is: submit is saving children class with all null fields when I dont fill any of then.
Question: How do I prevent that and save no children?
Example:
Classes:
class Parent {
String name
static hasOne = [children:Children]
}
class Children {
String name
static belongsTo = [parent : Parent]
static constraints = {
name nullable: true
}
}
HTML (.gsp):
<form controller="parent" action="save" method="post">
Parent Name:
<input type="text" name="name" value="parent name" />
Children Name:
<input type="text" name="children.name" />
<input type="submit" value="Save" />
</form>
Relational Tables:
Parent(id, name)
Children(id, name, parent_id)
Controller:
def save(Parent parent) {
parent.save()
}
Submit and Save:
Form data sended:
name: 'parent name'
children.name: ''
Persisted values:
Parent(1, 'parent name')
Children(1, null, 1)
-----------------
What I want is: The save method (controller) to receive the Parent class without a Children when the children have all null fields. Or another clean alternative that makes me save only the Parent class (no "empty" children).
PS: I try to solve with "#JsonInclude(Include.NON_EMPTY)" at the children's name, but it didn't work