jaxb binding file for + <extension base="anyType"/>

[indra_4011]

Hi  i have xsd defination  
<element name="primaryKey" nillable="false">
<complexType mixed="false">  
     <complexContent mixed="false">
<extension base="anyType"/>
   </complexContent>
</complexType>
</element>
and i using binding file to
<jxb:bindings node="//xs:extension[@base='anyType']">
            <jxb:property>
                <jxb:baseType name="java.lang.Object"/>
            </jxb:property>
        </jxb:bindings> to generate the jaxb classes but i am unable to  do so its giving error
[xjc] [ERROR] Specified property customization is not used.
Please help