There is xsd inheritance!

Look into two classes:

package com;
public class SomeBase {
}

package com;
public class SomeChild extends SomeBase {
}

and result conversion into xsd:

<xs:complexType name="SomeChild">
<xs:complexContent>
<xs:extension base="java:SomeBase" xmlns:java="java:com"/>
</xs:complexContent>
</xs:complexType>
<xs:complexType name="SomeBase"/>