use of JAXB impl classes in databinding-jaxb

[Scott Kurz]

I noticed class,
org.apache.tuscany.sca.databinding.jaxb.BeanXMLStreamReaderImpl is invoking
a constructor of com.sun.xml.bind.v2.runtime.JAXBContextImpl:

        JAXBContextImpl context =
            new JAXBContextImpl(classes, null, Collections.<Class, Class>
emptyMap(), null, false, reader, false, false);
        RuntimeModelBuilder builder =
            new RuntimeModelBuilder(context, reader, Collections.<Class,
Class> emptyMap(), null);

Is there really a need to use the JAXB RI impl classes here?

I don't understand yet what the code is doing, but isn't it bad to create a
dependency on a specific version of the JAXB impl, rather than the  API in
the JAXB spec?

(I didn't see a discussion on this in searching the mailing list.. only some
details about a build break that had happened at one time.)

Scott