How to enable JAXB Simplify plugin in Eclipse

Question

In Eclipse with a JAXB project, I try to generate classes with the Simplify plugin enabled.

Simplify plugin

I've put the required annotation in the XSD file:

<xs:choice maxOccurs="unbounded">           
        <xs:element maxOccurs="unbounded" ref="ns1:flow" minOccurs="0">
            <xs:annotation>
                <xs:appinfo>
                    <simplify:as-element-property/>
                </xs:appinfo>
            </xs:annotation>
        </xs:element>
        <xs:element maxOccurs="unbounded" ref="ns1:state" minOccurs="0">
                        <xs:annotation>
                <xs:appinfo>
                    <simplify:as-element-property/>
                </xs:appinfo>
            </xs:annotation>
        </xs:element>
    </xs:choice> 

And add the -Xsimplify argument during generation:

But the XJC compiler return error "unrecognized parameter -Xsimplify"

I've already searching from the net for 2 days and still can't find a guide to enable the JAXB2-Basic plugin inside Eclipse. Please help!!.