How to represent null value as empty element with JAXB?

Question

My XSD structure is like the below:-

Answer 1

You should read nillable and minOccurs XSD element attributes because the difference between nil and an empty element is significant in XML. i.e. xsi:nil=true is similar to SQL NULL but having empty element represents the presents of an empty element. :)
I know it is confusing.

To fix your specific issue, if you are using JAXB serialization to generate that, i recommend reading How to instantiate an empty element with JAXB. The question itself shows you how to generate an empty element.