JAXB: Empty object content gives error when marshalling - jaxb

Question

Using com.sun.xml.bind jaxb-impl 2.2.6.
I've got parent and child object, what I would like to get after marshall is:
<parent/> or <parent></parent>
But what I get is an error like:
Caused by:
com.sun.xml.internal.bind.api.AccessorException: Object must have some value in its #XmlValue field: com.test.data.Child#....
Here is the code:
#XmlAccessorType(XmlAccessType.FIELD)
#XmlType(name = "", propOrder = {"content"})
#XmlRootElement(name = "child")
public class Child {
#XmlValue
protected String content;
public String getContent() {
return content;
}
}
...
Then
#XmlAccessorType(XmlAccessType.FIELD)
#XmlType(name = "", propOrder = {"child"})
#XmlRootElement(name = "parent")
public class Parent {
protected Child child;
public Child getChild() {
return child;
}
}
What I do is (that's because I want to be able to "maybe" fill the content of child later):
if(parent.getChild == null)
parent.setChild(new Child());
Then, when I try to marshall, I get the error seen above.
If I try:
if(parent.getChild == null) {
Child child = new Child();
child.setContent("");
parent.setChild(child);
}
Then I get the expected:
<parent><child></child></parent>
And I can get what I want by never setting the child object in its parent (so no parent.setChild(...)), but as stated above, it would save me time to set it earlier.
Basically I am trying to do exactly the opposite as in the post:
JAXB: Empty string does not produce empty element
Is there anything I am doing wrong, or maybe something I did not setup correctly?
Thanks,
Yoann
Edit:
Is there any other way than to either:
- Set it back to null later: parent.setChild(null);
- Never set it as an object in the first place