Remove or replace Sun vendor specific import on jaxb-impl com.sun.xml.bind.marshaller.CharacterEscapeHandler

The current sitemap plugin has an explicit dependency (although provided) on com.sun.xml.bind:jaxb-impl:jar:2.1.13 and needs this to implement
public class org.onehippo.forge.sitemap.components.model.SiteMapCharacterEscapeHandler implements com.sun.xml.bind.marshaller.CharacterEscapeHandler;

With now using Java 7 as a minimum however, CMS 7.9 no longer needs and nor will bundle and 'provide' a jaxb-impl jar.

The above explicit dependency, and vendor specific import thus seems undesirable now, and will rely on the underlying JRE to provide this class (thus tying it to a Sun/Oracle JRE only).

It is therefore preferred that this usage is re-considered and if possible replaced with a non-vendor specific solution.
Maybe that will be difficult using jaxb but possibly an alterative marshalling mechanism can be considered?. Maybe json?